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Plots from Rivet analyses

Invariant cross section of neutral pions at mid-rapidity in $8\,$TeV pp collisions (ALICE_2017_I1620477)

Inspire | HepData | Eur. Phys. J. C (2018) 78: 263 | 10.1140/epjc/s10052-018-5612-8 | arXiv:hep-ex/1708.08745

Transverse momentum spectra of neutral pions and $\eta$ mesons measured at $0.3<p_T<35 GeV/c$ and $0.5<p_T<35 GeV/c$, respectively, and the ratio $\pi^{0}/\eta$, obtained at mid-rapidity in $pp$ collisions at $\sqrt(s) = 8\,$TeV with ALICE at the LHC.

Invariant cross section of neutral pions measured at mid-rapidity in pp collisions at $2.76\,$TeV. (ALICE_2017_I1512110)

Inspire | HepData

Transverse momentum spectra of neutral pions and $\eta$ mesons measured at 0.4<p_T<40 GeV/c and 0.6<p_T<20 GeV/c, respectively, and the ratio $\pi^{0}/\eta$, obtained at mid-rapidity in pp collisions at $\sqrt(s) = 2.76\,$TeV with ALICE at the LHC.

Transverse momentum spectra of pions, kaons and protons in $pp$ collisions at 7 TeV (ALICE_2015_I1357424)

Inspire | HepData

Obtaining the transverse momentum spectra of primary pions, kaons and protons in $pp$ collisions at $\sqrt{s} = 7$ TeV with ALICE at the LHC. K/pi and p/pi ratios are also included.

Production of $\Sigma(1385)^{\pm}$ and $\Xi(1530)^{0}$ in proton-proton collisions at $\sqrt{s} =$ 7 TeV (ALICE_2014_I1300380)

Inspire | HepData

Transverse momentum spectra $\frac{1}{N_{\rm inel}} \frac{{\rm d}^2N}{{\rm d}p_{\rm T}{\rm d}y}$ of $\Sigma(1385)^{\pm}$, $\overline{\Sigma}(1385)^{\pm}$ and $(\Xi(1530)^{0}+\overline{\Xi}(1530)^{0})/2$ at mid-rapidity ($|y| < 0.5$) in inelastic proton-proton collisions at $\sqrt{s} =$ 7 TeV

Measurement of inelastic, single- and double-diffraction cross sections in proton--proton collisions at the LHC with ALICE (ALICE_2012_I1181770)

Inspire | HepData | arXiv:1208.4968 [hep-ex]

Measurements of cross-sections of inelastic and diffractive processes in proton-proton collisions at $\sqrt{s} = 900$, 2760 and 7000 GeV. The fractions of diffractive processes in inelastic collisions were determined from a study of gaps in charged particle pseudorapidity distributions. Single-diffractive events are selected with $M_{X} < 200\;\text{GeV}/c^2$ and double-diffractive events defined as NSD events with $\Delta\eta > 3$. To measure the inelastic cross-section, beam properties were determined with van der Meer scans using a simulation of diffraction adjusted to data. Note that these are experimental approximations to theoretical concepts -- it is not totally clear whether the data point values are model-independent.

pT of neutral pions and $\eta$ mesons in $pp$ collisions at $7\,$TeV and $0.9\,$TeV (ALICE_2012_I1116147)

Inspire | HepData | Phys.Lett. B717 (2012) 162-172 | doi:10.1016/j.physletb.2012.09.015 | arXiv:hep-ex/1205.5724

Transverse momentum spectra of neutral pions and $\eta$ mesons and the ratio $\pi^0/\eta$, obtained at mid-rapidity in pp collisions at $\sqrt{s} = 7\,$TeV with ALICE at the LHC. The transverse momentum spectrum of neutral pions is also given for $\sqrt{s} = 0.9\,$TeV.

Transverse momentum spectra of pions, kaons and protons in pp collisions at 0.9 TeV (ALICE_2011_S8945144)

Inspire | HepData | Eur.Phys.J.C71:1655,2011. | arXiv:1101.4110 [hep-ex]

Obtaining the transverse momentum spectra of pions, kaons and protons in $pp$ collisions at $\sqrt{s} = 0.9$ TeV with ALICE at the LHC. Mean transverse momentum as a function of the mass of the emitted particle is also included.

Strange particle production in proton-proton collisions at $\sqrt{s} = 0.9$ TeV with ALICE at the LHC. (ALICE_2011_S8909580)

Inspire | HepData | Eur.Phys.J.C71:1594,2011.

Tranverse momentum spectra of strange particles ($K^0_S$, $\Lambda$, $\phi$ and $\Xi$) in $pp$ collisions at $\sqrt{s} = 0.9$\;TeV with ALICE at the LHC. The ratio of cross-sections as a function of pT for $\Lambda/K^0_S$ is also included.

Charged particle $\langle p_\perp \rangle$ vs. $N_\text{ch}$ in $pp$ collisions at 900 GeV (ALICE_2010_S8706239)

Inspire | HepData | Phys.Lett.B693:53-68,2010 | arXiv:1007.0719 [hep-ex]

ALICE measurement of $\langle p_\perp \rangle$ vs. $N_\text{ch}$ and invariant particle yield (as function of $p_\perp$) in proton-proton collisions at $\sqrt{s} = 900\;\text{GeV}$.

Pseudorapidities at three energies, charged multiplicity at 7 TeV (ALICE_2010_S8625980)

Inspire | HepData | Eur.Phys.J. C68 (2010) 345-354 | arXiv:1004.3514 [hep-ex]

This is an ALICE publication with pseudorapities for 0.9, 2.36 and $7\;\text{TeV}$ and the charged multiplicity at $7\;\text{TeV}$. The analysis requires at least on charged particle in the event. Only the INEL distributions are considered here

Charged particle multiplicities at 0.9 and 2.36\;TeV in three different pseudorapidity intervals (ALICE_2010_S8624100)

Inspire | HepData | Eur.Phys.J.C68:89-108,2010 | arXiv:1004.3034 [hep-ex]

This is an ALICE analysis where charged particle multiplicities (including the zero bin) have been measured in three different pseudorapidity intervals ($|\eta|<0.5; |\eta|<1.0; |\eta|<1.3$. Only the INEL distributions have been considered here, i.e. this analysis can only be meaningfully compared to PYTHIA 6 with diffractive processes disabled. The data were taken at 900 and 2360\;GeV.

g \to bb at 13 TeV (ATLAS_2018_I1711114)

Inspire | HepData | Phys.Rev. D99 (2019) no.5, 052004 | doi:10.1103/PhysRevD.99.052004 | arXiv:1812.09283 [hep-ex]

The fragmentation of high-energy gluons at small opening angles is largely unconstrained by present measurements. Gluon splitting to $b$-quark pairs is a unique probe into the properties of gluon fragmentation because identified $b$-tagged jets provide a proxy for the quark daughters of the initial gluon. In this study, key differential distributions related to the $g\to b\bar{b}$ process are measured using 33fb$^{-1}$ of $\sqrt{s}=13$ TeV $pp$ collision data recorded by the ATLAS experiment at the LHC in 2016. Jets constructed from charged-particle tracks, clustered with the anti-$k_\text{t}$ jet algorithm with radius parameter $R=0.2$, are used to probe angular scales below the $R=0.4$ jet radius. The observables are unfolded to particle level in order to facilitate direct comparisons with predictions from present and future simulations. Multiple significant differences are observed between the data and parton shower Monte Carlo predictions, providing input to improve these predictions of the main source of background events in analyses involving boosted Higgs bosons decaying into $b$-quarks.

ttbb at 13 TeV (ATLAS_2018_I1705857)

Inspire | HepData | submitted to JHEP | arXiv:1811.12113 [hep-ex]

This paper presents measurements of $t\bar{t}$ production in association with additional $b$-jets in $pp$ collisions at the LHC at a centre-of-mass energy of 13 TeV. The data were recorded with the ATLAS detector and correspond to an integrated luminosity of 36.1 fb$^{-1}$. Fiducial cross-section measurements are performed in the dilepton and lepton-plus-jets $t\bar{t}$ decay channels. Results are presented at particle level in the form of inclusive cross-sections of $t\bar{t}$ final states with three and four $b$-jets as well as differential cross-sections as a function of global event properties and properties of $b$-jet pairs. The measured inclusive fiducial cross-sections generally exceed the $t\bar{t}b\bar{b}$ predictions from various next-to-leading-order matrix element calculations matched to a parton shower but are compatible within the total uncertainties. The experimental uncertainties are smaller than the uncertainties in the predictions. Comparisons of state-of-the-art theoretical predictions with the differential measurements are shown and good agreement with data is found for most of them.

Differential $t\bar{t}$ $l$+jets cross-sections at 13 TeV (ATLAS_2018_I1656578)

Inspire | HepData | Submitted to JHEP | arXiv:1802.06572 [hep-ex]

Measurements of differential cross sections of top quark pair production in association with jets by the ATLAS experiment at the LHC are presented. The measurements are performed as functions of the top quark transverse momentum, the transverse momentum of the top quark-antitop quark system and the out-of-plane transverse momentum using data from pp collisions at $\sqrt{s}=13$ TeV collected by the ATLAS detector at the LHC in 2015 and corresponding to an integrated luminosity of 3.2 $\text{fb}^{-1}$. The top quark pair events are selected in the lepton (electron or muon) + jets channel. The measured cross sections, which are compared to several predictions, allow a detailed study of top quark production.

All-hadronic boosted ttbar at 13 TeV (ATLAS_2018_I1646686)

Inspire | HepData | doi:10.17182/hepdata.81709.v1 | arXiv:1801.02052 [hep-ex]

Measurements are made of differential cross-sections of highly boosted pair-produced top quarks as a function of top-quark and $t\bar{t}$ system kinematic observables using proton--proton collisions at a center-of-mass energy of $\sqrt{s}=13$ TeV. The data set corresponds to an integrated luminosity of 36.1 fb${}^{-1}$, recorded in 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider. Events with two large-radius jets in the final state, one with transverse momentum pT>500 GeV and a second with $p_\text{T} > 350$ GeV, are used for the measurement. The top-quark candidates are separated from the multijet background using jet substructure information and association with a $b$-tagged jet. The measured spectra are corrected for detector effects to a particle-level fiducial phase space and a parton-level limited phase space, and are compared to several Monte Carlo simulations by means of calculated $\chi^2$ values. The cross-section for $t\bar{t}$ production in the fiducial phase-space region is 292$\pm$7 (stat)$\pm$76(syst) fb, to be compared to the theoretical prediction of 384$\pm$36 fb.

ATLAS Inclusive jet and dijet cross section measurement at sqrt(s)=13TeV (ATLAS_2018_I1634970)

Inspire | HepData | JHEP 1805 (2018) 195 | arXiv:1711.02692

Inclusive jet and dijet cross-sections are measured in proton-proton collisions at a centre-of-mass energy of 13 TeV. The measurement uses a dataset with an integrated luminosity of 3.2 fb$^{-1}$ recorded in 2015 with the ATLAS detector at the Large Hadron Collider. Jets are identified using the anti-$k_\text{t}$ algorithm with a radius parameter value of $R = 0.4$. The inclusive jet cross-sections are measured double-differentially as a function of the jet transverse momentum, covering the range from 100 GeV to 3.5 TeV, and the absolute jet rapidity up to $|y| = 3$. The double-differential dijet production cross-sections are presented as a function of the dijet mass, covering the range from 300 GeV to 9 TeV, and the half absolute rapidity separation between the two leading jets within $|y| < 3$, $y^\ast$, up to $y^\ast = 3$. Next-to-leading-order, and next-to-next-to-leading-order for the inclusive jet measurement, perturbative QCD calculations corrected for non-perturbative and electroweak effects are compared to the measured cross-sections.

Dileptonic $t\bar{t}$ at 8 TeV (ATLAS_2017_I1626105)

Inspire | HepData | Eur.Phys.J. C77 (2017) no.11, 804 | doi:10.1140/epjc/s10052-017-5349-9 | arXiv:1709.09407 [hep-ex]

This paper presents single lepton and dilepton kinematic distributions measured in dileptonic $t\bar{t}$ events produced in 20.2 fb${}^{-1}$ of $\sqrt{s} = 8$ TeV $pp$ collisions recorded by the ATLAS experiment at the LHC. Both absolute and normalised differential cross-sections are measured, using events with an opposite-charge $e\mu$ pair and one or two $b$-tagged jets. The cross-sections are measured in a fiducial region corresponding to the detector acceptance for leptons, and are compared to the predictions from a variety of Monte Carlo event generators, as well as fixed-order QCD calculations, exploring the sensitivity of the cross-sections to the gluon parton distribution function. Some of the distributions are also sensitive to the top quark pole mass, a combined fit of NLO fixed-order predictions to all the measured distributions yields a top quark mass value of $m_t^\text{pole} = 173.2 \pm 0.9 \pm 0.8 \pm 1.2$ GeV, where the three uncertainties arise from data statistics, experimental systematics, and theoretical sources.

Study of ordered hadron chains at 7 TeV (ATLAS_2017_I1624693)

Inspire | HepData | Phys.Rev. D96 (2017) no.9, 092008 | doi:10.1103/PhysRevD.96.092008 | arXiv:1709.07384 [hep-ex]

The analysis of the momentum difference between charged hadrons in high-energy proton-proton collisions is performed in order to study coherent particle production. The observed correlation pattern agrees with a model of a helical QCD string fragmenting into a chain of ground-state hadrons. A threshold momentum difference in the production of adjacent pairs of charged hadrons is observed, in agreement with model predictions. The presence of low-mass hadron chains also explains the emergence of charge-combination-dependent two-particle correlations commonly attributed to Bose-Einstein interference. The data sample consists of 190 $\mu\text{b}^{-1}$ of minimum-bias events collected with proton-proton collisions at a center-of-mass energy $\sqrt{s}$ = 7 TeV in the early low-luminosity data taking with the ATLAS detector at the LHC.

Resolved and boosted ttbar l+jets cross sections at 13 TeV (ATLAS_2017_I1614149)

Inspire | HepData | JHEP 1711 (2017) 191 | doi:10.1007/JHEP11(2017)1 | arXiv:1708.00727 [hep-ex]

Measurements of differential cross-sections of top-quark pair production in fiducial phase-spaces are presented as a function of top-quark and $t\bar{t}$ system kinematic observables in proton-proton collisions at a centre-of-mass energy of $\sqrt{s} = 13$ TeV. The data set corresponds to an integrated luminosity of 3.2 fb${}^{-1}$, recorded in 2015 with the ATLAS detector at the CERN Large Hadron Collider. Events with exactly one electron or muon and at least two jets in the final state are used for the measurement. Two separate selections are applied that each focus on different top-quark momentum regions, referred to as resolved and boosted topologies of the $t\bar{t}$ final state. The measured spectra are corrected for detector effects and are compared to several Monte Carlo simulations by means of calculated $\chi^2$ and $p$-values.

Multijet transverse energy-energy correlations (TEEC) at 8 TeV (ATLAS_2017_I1609253)

Inspire | HepData | submitted to EPJC | arXiv:1707.02562 [hep-ex]

Measurements of transverse energy-energy correlations and their associated asymmetries in multi-jet events using the ATLAS detector at the LHC are presented. The data used correspond to $\sqrt{s} = 8$ TeV proton-proton collisions with an integrated luminosity of 20.2 fb$^{-1}$. The results are presented in bins of the scalar sum of the transverse momenta of the two leading jets, unfolded to the particle level and compared to the predictions from Monte Carlo simulations. A comparison with next-to-leading-order perturbative QCD is also performed, showing excellent agreement within the uncertainties. From this comparison, the value of the strong coupling constant is extracted for different energy regimes, thus testing the running of $\alpha_\text{s}(\mu)$ predicted in QCD up to scales over 1 TeV. A global fit to the transverse energy-energy correlation distributions yields $\alpha_\text{s}(m_Z) = 0.1162\pm 0.0011\text{(exp.)}^{+0.0084}_{-0.0070}\text{(theo.)}$, while a global fit to the asymmetry distributions yields a value of $\alpha_\text{s}(m_Z) = 0.1196\pm 0.0013\text{(exp.)}^{+0.0075}_{-0.0045}\text{(theo.)}$.

ttbar + gamma at 8 TeV (ATLAS_2017_I1604029)

Inspire | HepData | JHEP 1711 (2017) 086 | doi:10.1007/JHEP11(2017) | arXiv:1706.03046 [hep-ex]

The cross section of a top-quark pair produced in association with a photon is measured in proton-proton collisions at a centre-of-mass energy of $\sqrt{s} = 8$ TeV with 20.2 fb${}^{-1}$ of data collected by the ATLAS detector at the Large Hadron Collider in 2012. The measurement is performed by selecting events that contain a photon with transverse momentum $p_\text{T} > 15$ GeV, an isolated lepton with large transverse momentum, large missing transverse momentum, and at least four jets, where at least one is identified as originating from a $b$-quark. The production cross section is measured in a fiducial region close to the selection requirements. It is found to be $139 \pm 7$ (stat.) $\pm 17$ (syst.) fb, in good agreement with the theoretical prediction at next-to-leading order of $151 \pm 24$ fb. In addition, differential cross sections in the fiducial region are measured as a function of the transverse momentum and pseudorapidity of the photon.

Track-based underlying event at 13 TeV in ATLAS (ATLAS_2017_I1509919)

Inspire | HepData | arXiv:1701.05390

We present charged-particle distributions sensitive to the underlying event, measured by the ATLAS detector in proton-proton collisions at a centre-of-mass energy of 13 TeV, in low-luminosity Large Hadron Collider fills corresponding to an integrated luminosity of 1.6 nb${}^{-1}$. The distributions were constructed using charged particles with absolute pseudorapidity less than 2.5 and with transverse momentum greater than 500 MeV, in events with at least one such charged particle with transverse momentum above 1 GeV. These distributions characterise the angular distribution of energy and particle flows with respect to the charged particle with highest transverse momentum, as a function of both that momentum and of charged-particle multiplicity. The results have been corrected for detector effects and are compared to the predictions of various Monte Carlo event generators, experimentally establishing the level of underlying-event activity at LHC Run 2 energies and providing inputs for the development of event generator modelling. The current models in use for UE modelling typically describe this data to 5% accuracy, compared with data uncertainties of less than 1%.

ttbar + jets at 13 TeV (ATLAS_2017_I1495243)

Inspire | HepData | Eur.Phys.J. C77 (2017) no.4, 220 | doi:10.1140/epjc/s10052-017-4766-0 | arXiv:1610.09978 [hep-ex]

Measurements of jet activity in top-quark pair events produced in proton--proton collisions are presented, using 3.2 fb$^{-1}$ of $pp$ collision data at a centre-of-mass energy of 13 TeV collected by the ATLAS experiment at the Large Hadron Collider. Events are chosen by requiring an opposite-charge $e\mu$ pair and two $b$-tagged jets in the final state. The normalised differential cross-sections of top-quark pair production are presented as functions of additional-jet multiplicity and transverse momentum, $p_\text{T}$. The fraction of signal events that do not contain additional jet activity in a given rapidity region, the gap fraction, is measured as a function of the $p_\text{T}$ threshold for additional jets, and is also presented for different invariant mass regions of the $e\mu b\bar{b}$ system. All measurements are corrected for detector effects and presented as particle-level distributions compared to predictions with different theoretical approaches for QCD radiation. While the kinematics of the jets from top-quark decays are described well, the generators show differing levels of agreement with the measurements of observables that depend on the production of additional jets.

Hard double-parton scattering in four-jet events at 7 TeV (ATLAS_2016_I1479760)

Inspire | HepData | arXiv:1608.01857 [hep-ex]

Inclusive four-jet events produced in $pp$ collisions at a centre-of-mass energy of $\sqrt{s} = 7$ TeV have been analysed for the presence of hard double-parton scattering using data corresponding to an integrated luminosity of $(37.3 \pm 1.3)$ $\mathrm{pb}^{-1}$, collected with the ATLAS detector at the LHC. The distributions of observables sensitive to the contribution of hard double-parton scattering are provided for events containing at least four jets with $p_{\mathrm{T}} \geq 20$ GeV and $\eta \leq 4.4$, and at least one of which has $p_{\text{T}} \geq 42.5$ GeV.

Dileptonic $e \mu$ $t\bar{t}$ early cross-section measurement at 13 TeV (ATLAS_2016_I1468168)

Inspire | HepData | Submitted to PLB | arXiv:1606.02699 [hep-ex]

This paper describes a measurement of the inclusive top quark pair production cross-section ($\sigma_{t\bar{t}}$) with a data sample of 3.2 fb${}^{-1}$ of proton-proton collisions at a centre-of-mass energy of $\sqrt{s}=13$ TeV, collected in 2015 by the ATLAS detector at the LHC. This measurement uses events with an opposite-charge electron-muon pair in the final state. Jets containing $b$-quarks are tagged using an algorithm based on track impact parameters and reconstructed secondary vertices. The numbers of events with exactly one and exactly two $b$-tagged jets are counted and used to determine simultaneously $\sigma_{t\bar{t}}$ and the efficiency to reconstruct and $b$-tag a jet from a top quark decay, thereby minimising the associated systematic uncertainties. The cross-section is measured to be: $\sigma_{t\bar{t}} = 818 \pm 8$ (stat) $\pm 27$ (syst) $\pm 19$ (lumi) $\pm 12$ (beam) pb, where the four uncertainties arise from data statistics, experimental and theoretical systematic effects, the integrated luminosity and the LHC beam energy, giving a total relative uncertainty of 4.4\%. The result is consistent with theoretical QCD calculations at next-to-next-to-leading order. A fiducial measurement corresponding to the experimental acceptance of the leptons is also presented.

Measurement of the inelastic proton--proton cross-section at $\sqrt{s} = 13\,\text{TeV}$ (ATLAS_2016_I1468167)

Inspire | HepData | arXiv:1606.02625 [hep-ex]

Inelastic cross-section is measured for $\xi > 1 \times 10^{-6}$, where $\xi=M_X^2/s$ is calculated from the invariant mass, $M_X$, of hadrons selected using the largest rapidity gap in the event.

Track-based minimum bias with low-pT tracks at 13 TeV (ATLAS_2016_I1467230)

Inspire | HepData | Eur.Phys.J. C76 (2016) no.9, 502 | doi:10.1140/epjc/s10052-016-4335-y | arXiv:1606.01133 [hep-ex]

Measurements of distributions of charged particles produced in proton-proton collisions with a centre-of-mass energy of 13 TeV are presented. The data were recorded by the ATLAS detector at the LHC and correspond to an integrated luminosity of 151 $\mu$b$^{-1}$. The particles are required to have a transverse momentum greater than 100 MeV and an absolute pseudorapidity less than 2.5. The charged-particle multiplicity, its dependence on transverse momentum and pseudorapidity and the dependence of the mean transverse momentum on multiplicity are measured in events containing at least two charged particles satisfying the above kinematic criteria. The results are corrected for detector effects and compared to the predictions from several Monte Carlo event generators.

Charge asymmetry in top quark pair production in dilepton channel (ATLAS_2016_I1449082)

Inspire | HepData | Phys.Rev. D94 (2016) no.3, 032006 | doi:10.1103/PhysRevD.94.032006 | arXiv:1604.05538 [hep-ex]

Measurements of the top-antitop quark pair production charge asymmetry in the dilepton channel are presented using data corresponding to an integrated luminosity of $20.3\;\text{fb}^{-1}$ from $pp$ collisions at a center-of-mass energy of $\sqrt{s} = 8$ TeV collected with the ATLAS detector at the Large Hadron Collider at CERN. Inclusive and differential measurements as a function of the invariant mass, transverse momentum, and longitudinal boost of the $t\bar{t}$ system are performed both in the full phase space and in a fiducial phase space closely matching the detector acceptance (at least 2 leptons and 2 jets with $p_\text{T} > 25$ GeV and $|\eta| < 2.5$). Two observables are studied: $A_C^{\ell\ell}$ based on the selected leptons and $A_C^{t\bar{t}}$ based on the reconstructed $t\bar{t}$ final state. The unfolded distributions of $\Delta|\eta| = |\eta|_{\ell^+} - |\eta|_{\ell^-}$ and $\Delta|y| = |y|_\text{top} - |y|_\text{antitop}$ are provided. USERS SHOULD NOTE THAT EXPLICIT RECONSTRUCTION OF INDIVIDUAL STANDARD MODEL NEUTRINOS IS USED IN THIS ANALYSIS ROUTINE TO MATCH THE MONTE-CARLO-BASED CORRECTION TO THE FIDUCIAL REGION APPLIED IN THE PAPER.

Track-based minimum bias at 8 TeV (ATLAS_2016_I1426695)

Inspire | HepData | Eur.Phys.J. C76 (2016) no.7, 403 | doi:10.1140/epjc/s10052-016-4203-9 | arXiv:1603.02439 [hep-ex]

This paper presents measurements of distributions of charged particles which are produced in proton-proton collisions at a centre-of-mass energy of $\sqrt{s} = 8$ TeV and recorded by the ATLAS detector at the LHC. A special dataset recorded in 2012 with a small number of interactions per beam crossing (below 0.004) and corresponding to an integrated luminosity of 160 $\mu\text{b}^{-1}$ was used. A minimum-bias trigger was utilised to select a data sample of more than 9 million collision events. The multiplicity, pseudorapidity, and transverse momentum distributions of charged particles are shown in different regions of kinematics and charged-particle multiplicity, including measurements of final states at high multiplicity. The results are corrected for detector effects and are compared to the predictions of various Monte Carlo event generator models which simulate the full hadronic final state.

Track-based minimum bias at 13 TeV in ATLAS (ATLAS_2016_I1419652)

Inspire | HepData | arXiv:1602.01633 | doi:10.1016/j.physletb.2016.04.050 | Physics Letters B (2016), Vol. 758, pp. 67-88

Measurements from proton-proton collisions at centre-of-mass energy of $\sqrt{s} = 13$ TeV recorded with the ATLAS detector at the LHC. Events were collected using a single-arm minimum-bias trigger. The charged-particle multiplicity, its dependence on transverse momentum and pseudorapidity and the relationship between the mean transverse momentum and charged-particle multiplicity are measured. The observed distributions are corrected to well-defined phase-space regions ($p_\text{T} > 500$ MeV and $|\eta| < 2.5$ of the particles), using model-independent corrections.

Number of tracks in jets (ATLAS_2016_I1419070)

Inspire | HepData | arXiv:1602.00988 [hep-ex] | Eur.Phys.J. C76 (2016) no.6, 322 | doi:10.1140/epjc/s10052-016-4126-5

The number of charged particles inside jets is a widely used discriminant for identifying the quark or gluon nature of the initiating parton and is sensitive to both the perturbative and non-perturbative components of fragmentation. This analysis presents a measurement of the average number of charged particles with $p_\text{T}>500$ MeV inside high-momentum jets in dijet events using 20.3 fb${}^{-1}$ of data recorded with the ATLAS detector in $pp$ collisions at $\sqrt{s}=8$ TeV collisions at the LHC. The jets considered have transverse momenta from 50 GeV up to and beyond 1.5 TeV. The reconstructed charged-particle track multiplicity distribution is unfolded to remove distortions from detector effects.

Inclusive jet cross sections using early 13 TeV data (ATLAS_2016_CONF_2016_092)

ATLAS-CONF-2016-092

This note presents the measurement of inclusive-jet cross-sections in proton--proton collisions at a centre-of-mass energy of 13TeV. The measurement uses data corresponding to an integrated luminosity of 3.2 fb$^{-1}$ collected with the ATLAS detector at the Large Hadron Collider in 2015. Jets are clustered using the anti-$k_\text{t}$ algorithm with a radius parameter value of $R = 0.4$. Double differential inclusive-jet cross-sections are presented as a function of the jet transverse momentum, covering the range from 100 GeV to about 3.2 TeV, and of the absolute jet rapidity, up to $|y| = 3$. The predictions of next-to-leading-order QCD calculations using several parton distribution function (PDF) sets and corrected for non-perturbative and electroweak effects are compared to the measured cross-sections. The predictions are consistent with the measured cross-sections within uncertainties.

ttbar (to l+jets) differential cross sections at 8 TeV (ATLAS_2015_I1404878)

Inspire | HepData | Submitted to EPJC | arXiv:1511.04716 [hep-ex]

Measurements of normalized differential cross-sections of top-quark pair production are presented as a function of the top-quark, $t\bar{t}$ system and event-level kinematic observables in proton-proton collisions at a centre-of-mass energy of $\sqrt{s} = 8$ TeV. The observables have been chosen to emphasize the $t\bar{t}$ production process and to be sensitive to effects of initial- and final-state radiation, to the different parton distribution functions, and to non-resonant processes and higher-order corrections. The dataset corresponds to an integrated luminosity of 20.3 fb${}^{-1}$, recorded in 2012 with the ATLAS detector at the CERN Large Hadron Collider. Events are selected in the lepton$+$jets channel, requiring exactly one charged lepton and at least four jets with at least two of the jets tagged as originating from a $b$-quark. The measured spectra are corrected for detector effects and are compared to several Monte Carlo simulations. The results are in fair agreement with the predictions over a wide kinematic range. Nevertheless, most generators predict a harder top-quark transverse momentum distribution at high values than what is observed in the data. Predictions beyond NLO accuracy improve the agreement with data at high top-quark transverse momenta. Using the current settings and parton distribution functions, the rapidity distributions are not well modelled by any generator under consideration. However, the level of agreement is improved when more recent sets of parton distribution functions are used.

Boosted ttbar differential cross-section (ATLAS_2015_I1397637)

Inspire | HepData | Phys.Rev. D93 (2016) no.3, 032009 | doi:10.1103/PhysRevD.93.032009 | arXiv:1510.03818 [hep-ex]

The differential cross-section for pair production of top quarks with high transverse momentum is measured in 20.3fb${}^{-1}$ of proton-proton collisions at a center-of-mass energy of 8 TeV. The measurement is performed for $t\bar{t}$ events in the lepton+jets channel. The cross-section is reported as a function of the hadronically decaying top quark transverse momentum for values above 300 GeV. The hadronically decaying top quark is reconstructed as an anti-$k_\text{t}$ jet with radius parameter $R=1.0$ and identified with jet substructure techniques. The observed yield is corrected for detector effects to obtain a cross-section at particle level in a fiducial region close to the event selection.

$Wt$ at 8 TeV (ATLAS_2015_I1397635)

Inspire | HepData | JHEP01 (2016) 064 | doi:10.1007/JHEP01(2016)064 | arXiv:1510.03752 [hep-ex]

Fiducial cross-section for $Wt+t\bar{t}$ production in events with two leptons and exactly one jet, using an integrated luminosity of 20.3 fb${}^{-1}$ of proton-proton collisions at a centre-of-mass energy of 8 TeV at the Large Hadron Collider, collected with the ATLAS detector. The cross-section for the production of a top quark and a $W$ boson is measured in a fiducial acceptance requiring two leptons with $p_\perp > 25$ GeV and $|\eta| < 2.5$, one jet with $p_\perp > 20$ GeV and $|\eta| < 2.5$, and $E^\text{miss}_\text{T} > 20$ GeV, including both $Wt$ and top-quark pair events as signal. The measured value of the fiducial cross-section is $0.85 \pm 0.01$ (stat.) $\pm 0.07$ (syst.) $\pm 0.03$ (lumi.) pb.

Multijets at 8 TeV (ATLAS_2015_I1394679)

Inspire | HepData | arXiv:1509.07335 [hep-ex]

Differential cross sections for the production of at least four jets have been measured in proton-proton collisions at $\sqrt{s}=8$\,TeV at the Large Hadron Collider using the ATLAS detector. The dataset corresponds to an integrated luminosity of 20.3\,fb^{-1}. The cross sections are corrected for detector effects and presented as a function of the jet momenta, invariant masses, minimum and maximum opening angles and other kinematic variables.

Jet charge (ATLAS_2015_I1393758)

Inspire | HepData | Phys.Rev. D93 (2016) no.5, 052003 | doi:10.1103/PhysRevD.93.052003 | arXiv:1509.05190 [hep-ex]

The momentum-weighted sum of the charges of tracks associated to a jet is sensitive to the charge of the initiating quark or gluon. This paper presents a measurement of the distribution of momentum-weighted sums, called jet charge, in dijet events using 20.3 fb${}^{-1}$ of data recorded with the ATLAS detector at $\sqrt{s} = 8$ TeV in $pp$ collisions at the LHC. The jet charge distribution is unfolded to remove distortions from detector effects and the resulting particle-level distribution is compared with several models. The $p_\text{T}$ dependence of the jet charge distribution average and standard deviation are compared to predictions obtained with several leading-order and next-to-leading-order parton distribution functions. The data are also compared to different Monte Carlo simulations of QCD dijet production using various settings of the free parameters within these models. The chosen value of the strong coupling constant used to calculate gluon radiation is found to have a significant impact on the predicted jet charge. There is evidence for a $p_\text{T}$ dependence of the jet charge distribution for a given jet flavor. In agreement with perturbative QCD predictions, the data show that the average jet charge of quark-initiated jets decreases in magnitude as the energy of the jet increases.

$tt+b(b)$ at 8 TeV (ATLAS_2015_I1390114)

Inspire | HepData | Eur.Phys.J. C76 (2016) no.1, 11 | doi:10.1140/epjc/s10052-015-3852-4 | arXiv:1508.06868 [hep-ex]

Fiducial cross-sections for $t\bar{t}$ production with one or two additional $b$-jets are presented, using an integrated luminosity of 20.3 fb${}^{-1}$ of proton-proton collisions at a centre-of-mass energy of 8 TeV at the Large Hadron Collider, collected with the ATLAS detector. The cross-section times branching ratio for $t\bar{t}$ events with at least one additional $b$-jet is measured to be 950 $\pm$ 70 (stat.) ${}^{+240}_{-190}$ (syst.) fb in the lepton-plus-jets channel and 50 $\pm$ 10 (stat.) ${}^{+15}_{-10}$ (syst.) fb in the $e\mu$ channel. The cross-section times branching ratio for events with at least two additional $b$-jets is measured to be 19.3 $\pm$ 3.5 (stat.) $\pm$ 5.7 (syst.) fb in the dilepton channel ($e\mu$, $\mu\mu$, $ee$) using a method based on tight selection criteria, and 13.5 $\pm$ 3.3 (stat.) $\pm$ 3.6 (syst.) fb using a looser selection that allows the background normalisation to be extracted from data. The latter method also measures a value of 1.30 $\pm$ 0.33 (stat.) $\pm$ 0.28 (syst.)$\%$ for the ratio of $t\bar{t}$ production with two additional $b$-jets to $t\bar{t}$ production with any two additional jets. NB: When merging several output YODA files, the ratio (d02-x01-y01) needs to be reconstructed in a post-processing step.

Energy-energy correlation (ATLAS_2015_I1387176)

Inspire | HepData | arXiv:1508.01579 [hep-ex]

High transverse momentum jets produced in $pp$ collisions at a centre-of-mass energy of 7 TeV are used to measure the transverse energy--energy correlation function and its associated azimuthal asymmetry. The data were recorded with the ATLAS detector at the LHC in the year 2011 and correspond to an integrated luminosity of $158\,\text{pb}^{-1}$. The selection criteria demand the average transverse momentum of the two leading jets in an event to be larger than 250 GeV. The data are unfolded to the particle level. NB--If the routine is to be run on several samples (with different cross sections), the asymmetry has to be calculated again in a post-processing step using the merged output file.

Colour flow in hadronic top decay at 8 TeV (ATLAS_2015_I1376945)

Inspire | HepData | arXiv:1506.05629 [hep-ex]

The distribution and orientation of energy inside jets is predicted to be an experimental handle on colour connections between the hard-scatter quarks and gluons initiating the jets. This is a measurement of the distribution of one such variable, the jet pull angle. The pull angle is measured for jets produced in $t\bar{t}$ events with one $W$ boson decaying leptonically and the other decaying to jets using 20.3\,$\text{fb}^{-1}$ of data recorded with the ATLAS detector at a centre-of-mass energy of $\sqrt{s} = 8$\,TeV at the LHC. The jet pull angle distribution is corrected for detector resolution and acceptance effects.

Pseudo-top-antitop cross sections (ATLAS_2015_I1345452)

Inspire | HepData | arXiv:1502.05923 [hep-ex]

Various differential cross-sections are measured in top-quark pair ($t\bar{t}$) events produced in proton-proton collisions at a centre-of-mass energy of $\sqrt{s}=7$ TeV at the LHC with the ATLAS detector. These differential cross-sections are presented in a data set corresponding to an integrated luminosity of 4.6 fb$^{-1}$. The differential cross-sections are presented in terms of kinematic variables of a top-quark proxy referred to as the pseudo-top-quark whose dependence on theoretical models is minimal. The pseudo-top-quark can be defined in terms of either reconstructed detector objects or stable particles in an analogous way. The measurements are performed on $t\bar{t}$ events in the lepton+jets channel, requiring exactly one charged lepton and at least four jets with at least two of them tagged as originating from a $b$-quark. The hadronic and leptonic pseudo-top-quarks are defined via the leptonic or hadronic decay mode of the W boson produced by the top-quark decay in events with a single charged lepton. The cross-section is measured as a function of the transverse momentum and rapidity of both the hadronic and leptonic pseudo-top-quark as well as the transverse momentum, rapidity and invariant mass of the pseudo-top-quark pair system. The measurements are corrected for detector effects and are presented within a kinematic range that closely matches the detector acceptance.

Measurement of the inclusive jet cross-section at 7 TeV (ATLAS_2014_I1325553)

Inspire | HepData | arXiv:1410.8857 [hep-ex]

Measurement of the inclusive jet cross-section in proton--proton collisions at a centre-of-mass energy of 7 TeV using a data set corresponding to an integrated luminosity of 4.5/fb collected with the ATLAS detector at the Large Hadron Collider in 2011. Jets are identified using the anti-$k_t$ algorithm with radius parameter values of 0.4 and 0.6. The double-differential cross-sections are presented as a function of the jet transverse momentum and the jet rapidity, covering jet transverse momenta from 100 GeV to 2 TeV.

Measurements of jet vetoes and azimuthal decorrelations in dijet events produced in pp collisions at $\sqrt{s}$ = 7 TeV using the ATLAS detector (ATLAS_2014_I1307243)

Inspire | HepData | EPJ C74,3117 (2014) | doi:10.1140/epjc/s10052-014-3117-7 | arXiv:hep-ex/1407.5756

Additional jet activity in dijet events is measured using $pp$ collisions at ATLAS at a centre-of-mass energy of 7 TeV, for jets reconstructed using the anti-kt algorithm with radius parameter R=0.6. This is done using variables such as the fraction of dijet events without an additional jet in the rapidity interval bounded by the dijet subsystem and correlations between the azimuthal angles of the dijets. They are presented, both with and without a veto on additional jet activity in the rapidity interval, as a function of the mean transverse momentum of the dijets and of the rapidity interval size. The double differential dijet cross section is also measured as a function of the interval size and the azimuthal angle between the dijets. These variables probe differences in the approach to resummation of large logarithms when performing QCD calculations. The data are compared to POWHEG, interfaced to the PYTHIA 8 and HERWIG parton shower generators, as well as to HEJ with and without interfacing it to the ARIADNE parton shower generator. None of the theoretical predictions agree with the data across the full phase-space considered; however, POWHEG+PYTHIA 8 and HEJ+ARIADNE are found to provide the best agreement with the data. These measurements use the full data sample collected with the ATLAS detector in 7 TeV $pp$ collisions at the LHC and correspond to integrated luminosities of 36.1 pb$^-1$ and 4.5 fb$^-1$ for data collected during 2010 and 2011 respectively.

Measurement of jet multiplicity and transverse momentum spectra in top events using full 7 TeV ATLAS dataset (ATLAS_2014_I1304688)

Inspire | HepData | CERN-PH-EP-2014-114 | arXiv:1407.0891[hep-ex]

Measurement of the differential t$\bar{\mathrm t}$ production cross-section in 7 TeV proton-proton collisions in the single-lepton channel from ATLAS. The data comprise the full 2011 data sample corresponding to an integrated luminosity of $4.6\,\mathrm{fb}^{-1}$. The differential cross-sections are measured as a function of the jet multiplicity for up to eight jets using jet transverse momentum thresholds of 25, 40, 60, and 80 GeV, and as a function of jet transverse momentum up to the fifth leading jet. The results after background subtraction are corrected for all detector effects, within a kinematic range closely matched to the experimental acceptance.

Leading jet underlying event at 7 TeV in ATLAS (ATLAS_2014_I1298811)

Inspire | HepData | arXiv:1406.0392 | Eur.Phys.J. C74 (2014) 2965 | DOI:10.1140/epjc/s10052-014-2965-5

Underlying event measurements with the ATLAS detector at the LHC at a center-of-mass energy of 7 TeV, using the leading jet for event azimuthal orientation and constructing standard transverse region observables from both charged tracks and calorimeter clusters.

The differential production cross section of the $\phi(1020)$ meson in $\sqrt{s}=7$ TeV $pp$ collisions measured with the ATLAS detector (ATLAS_2014_I1282441)

Inspire | HepData | arXiv:1402.6162 [hep-ex] | Eur.Phys.J. C74 (2014) no.7, 2895

A measurement is presented of the $\phi \rightarrow K^+K^-$ production cross section at $\sqrt{s}$ = 7 TeV using pp collision data corresponding to an integrated luminosity of 383 $\mu$b$^{-1}$ collected with the ATLAS experiment at the LHC. Selection of $\phi(1020)$ mesons is based on the identification of charged kaons by their energy loss in the pixel detector. The differential cross section is measured as a function of the transverse momentum, $pT,\phi$, and rapidity, $y_\phi$, of the $\phi(1020)$ meson in the fiducial region 500 < $pT,\phi$ < 1200 MeV, |$y_\phi$| < 0.8, kaon $pT,K$ > 230 MeV and kaon momentum $p_K$ < 800 MeV. The integrated $\phi(1020)$ production cross section in this fiducial range is measured to be $\sigma_{\phi \rightarrow K^+K^-}$ = 570 \pm 8 (stat) \pm 66 (syst) \pm 20 (lumi) $\mu$b.

High-mass dijet cross section (ATLAS_2014_I1268975)

Inspire | HepData | arXiv:1312.3524 [hep-ex] | JHEP 1405 (2014) 059

Double-differential dijet cross sections measured in pp collisions at the LHC with a 7 TeV centre-of-mass energy are presented as functions of dijet mass and rapidity separation of the two highest-pT jets. These measurements are obtained using data corresponding to an integrated luminosity of 4.5/fb, recorded by the ATLAS detector in 2011. The data are corrected for detector effects so that cross sections are presented at the particle level. Cross sections are measured up to 5 TeV dijet mass using jets reconstructed with the anti-kt algorithm for values of the jet radius parameter of 0.4 and 0.6. The cross sections are compared with next-to-leading-order perturbative QCD calculations by NLOJET++ corrected to account for non-perturbative effects. Comparisons with POWHEG predictions, using a next-to-leading-order matrix element calculation interfaced to a parton-shower Monte Carlo simulation, are also shown. Electroweak effects are accounted for in both cases. The quantitative comparison of data and theoretical predictions obtained using various parameterizations of the parton distribution functions is performed using a frequentist method. An example setting a lower limit on the compositeness scale for a model of contact interactions is presented, showing that the unfolded results can be used to constrain contributions to dijet production beyond that predicted by the Standard Model.

Measurement of jet shapes in top quark pair events at $\sqrt{s} = 7$ TeV with ATLAS (ATLAS_2013_I1243871)

Inspire | HepData | arXiv:1307.5749 [hep-ex]

Measurement of jet shapes in top pair events in the ATLAS 7 TeV run. b-jets are shown to have a wider energy density distribution than light-quark induced jets.

Flavour composition of dijet events at 7 TeV (ATLAS_2012_I1188891)

Inspire | HepData | arXiv:1210.0441

The measurement of the flavour composition of dijet events produced in pp collisions at $\sqrt{s}=7\;\text{TeV}$ using the ATLAS detector. Six possible combinations of light, charm and bottom jets are identified in the dijet events, where the jet flavour is defined by the presence of bottom, charm or solely light flavour hadrons in the jet. The fractions of these dijet flavour states as functions of the leading jet transverse momentum in the range 40 GeV to 500 GeV and jet rapidity $|y| < 2.1$ are measured.

Pseudorapidity dependence of the total transverse energy at 7 TeV (ATLAS_2012_I1183818)

Inspire | HepData | arXiv:1208.6256

The measurement of the sum of the transverse energy of particles as a function of particle pseudorapidity, eta, in proton-proton collisions at a centre-of-mass energy, $\sqrt{s} = 7\;\text{TeV}$ using the ATLAS detector at the Large Hadron Collider. The measurements are performed in the region $|\eta| < 4.8$ for two event classes: those requiring the presence of particles with a low transverse momentum and those requiring particles with a significant transverse momentum (dijet events where both jets have $E_T > 20$ GeV). In the second dataset measurements are made in the region transverse to the hard scatter.

Studies of the underlying event at 7 TeV with track-jets (ATLAS_2012_I1125575)

Inspire | HepData | arXiv:1208.0563 [hep-ex]

Distributions sensitive to the underlying event are studied in events containing one or more charged particles. Jets are reconstructed using the anti-$k_t$ algorithm with radius parameter $R$ varying between 0.2 and 1.0. Distributions of the charged-particle multiplicity, the scalar sum of the transverse momentum of charged particles, and the average charged-particle pT are measured as functions of $p_\perp^\text{jet}$ in regions transverse to and opposite the leading jet for $4 \text{GeV} < p_\perp^\text{jet} < 100 \text{GeV}$. In addition, the $R$-dependence of the mean values of these observables is studied.

Measurement of charged-particle event shape variables (ATLAS_2012_I1124167)

Inspire | HepData | arXiv:1207.6915 | Phys.Rev. D88 (2013) 032004 | 10.1103/PhysRevD.88.032004

The measurement of charged-particle event shape variables is presented in inclusive inelastic $pp$ collisions at a center-of-mass energy of 7 TeV using the ATLAS detector at the LHC. The observables studied are the transverse thrust, thrust minor, and transverse sphericity, each defined using the final-state charged particles momentum components perpendicular to the beam direction. Events with at least six charged particles are selected by a minimum-bias trigger. In addition to the differential distributions, the evolution of each event shape variable as a function of the leading charged-particle transverse momentum, charged-particle multiplicity, and summed transverse momentum is presented.

Jet shapes and jet masses (ATLAS_2012_I1119557)

Inspire | HepData | Phys.Rev. D86 (2012) 072006 | doi:10.1103/PhysRevD.86.072006 | arXiv:1206.5369 [hep-ex]

Measurements are presented of the properties of high transverse momentum jets, produced in proton-proton collisions at a center-of-mass energy of $\sqrt{s} = 7$\;TeV. Jet mass, width, eccentricity, planar flow and angularity are measured for jets reconstructed using the anti-$k_t$ algorithm with distance parameters $R = 0.6$ and 1.0, with transverse momentum $pT > 300$\;GeV and pseudorapidity $|\eta| < 2$.

$b$-hadron production cross-section using decays to $D^*\mu^-X$ at $\sqrt{s} = 7$\;TeV (ATLAS_2012_I1118269)

Inspire | HepData | arXiv:1206.3122 [hep-ex]

Measurement of $b$-hadron production cross section using 3.3\;pb$^{-1}$ of integrated luminosity, collected during the 2010 LHC run. The $b$-hadrons are selected by partially reconstructing $D^{*}\mu^-X$ final states using only direct semileptonic decays of $b$ to $D^*\mu^-X$. Differential cross sections as functions of $p_\perp$ and $|\eta|$.

Measurement of ttbar production with a veto on additional central jet activity (ATLAS_2012_I1094568)

Inspire | HepData | arXiv:1203.5015 [hep-ex] | Eur.Phys.J. C72 (2012) 2043

A measurement of the additional jet activity in dileptonic ttbar events. The fraction of events passing a veto requirement are shown as a function the veto scale for four central rapidity intervals. Two veto definitions are used: events are vetoed if they contain an additional jet in the rapidity interval with transverse momentum above a threshold, or alternatively, if the scalar transverse momentum sum of all additional jets in the rapidity interval is above a threshold.

Jet mass and substructure of inclusive jets at 7 TeV (ATLAS_2012_I1094564)

Inspire | HepData | JHEP 1205 (2012) 128 | doi:10.1007/JHEP05(2012)128 | arXiv:1203.4606 [hep-ex]

In this analysis, the assumption that the internal substructure of jets generated by QCD radiation is well understood is tested on an inclusive sample of jets recorded with the ATLAS detector in 2010, which corresponds to 35 $pb^{-1}$ of $pp$ collisions delivered by the LHC at $\sqrt{s} = 7$ TeV. Jet invariant mass, $k_{t}$ splitting scales and $N$-subjettiness variables are presented for anti-$k_{t}$ $R = 1.0$ jets and Cambridge-Aachen $R = 1.2$ jets. Jet invariant-mass spectra for Cambridge-Aachen $R = 1.2$ jets after a splitting and filtering procedure are also presented.

Forward-backward and $\phi$ correlations at 900 GeV and 7 TeV (ATLAS_2012_I1093734)

Inspire | HepData | JHEP 1207 (2012) 019 | doi:10.1007/JHEP07(2012)019 | arXiv:1203.3100 [hep-ex]

Using inelastic proton-proton interactions at $\sqrt{s}$ = 900 GeV and 7 TeV, recorded by the ATLAS detector at the LHC, measurements have been made of the correlations between forward and backward charged-particle multiplicities and, for the first time, between forward and backward charged-particle summed transverse momentum. In addition, jet-like structure in the events is studied by means of azimuthal distributions of charged particles relative to the charged particle with highest transverse momentum in a selected kinematic region of the event.

Azimuthal ordering of charged hadrons (ATLAS_2012_I1091481)

Inspire | HepData | CERN-PH-EP-2011-197 | arXiv:1203.0419 [hep-ex]

Measurement of the ordering of charged hadrons in the azimuthal angle relative to the beam axis at the Large Hadron Collider (LHC). A spectral analysis of correlations between longitudinal and transverse components of the momentum of the charged hadrons is performed. Data were recorded with the ATLAS detector at centre-of-mass energies of $\sqrt{s} = 900\;\text{GeV}$ and $\sqrt{s} = 7\;\text{TeV}$. The correlations measured in a phase space region dominated by low-$p_\perp$ particles are not well described by conventional models of hadron production. The measured spectra show features consistent with the fragmentation of a QCD string represented by a helix-like ordered gluon chain.

Rapidity gap cross sections measured with the ATLAS detector in $pp$ collisions at $\sqrt{s} = 7$ TeV. (ATLAS_2012_I1084540)

Inspire | HepData | arXiv:1201.2808 [hep-ex]

Pseudorapidity gap distributions in proton-proton collisions at $\sqrt{s} = 7$ TeV are studied using a minimum bias data sample with an integrated luminosity of 7.1 inverse microbarns. Cross sections are measured differentially in terms of $\Delta \eta_F$, the larger of the pseudorapidity regions extending to the limits of the ATLAS sensitivity, at $\eta = \pm 4.9$, in which no final state particles are produced above a transverse momentum threshold $p_\perp$ cut. The measurements span the region $0 < \Delta \eta_F < 8$ for $200 < p_T\text{ cut} < 800\;\text{MeV}$. At small $\Delta \eta_F$, the data test the reliability of hadronisation models in describing rapidity and transverse momentum fluctuations in final state particle production. The measurements at larger gap sizes are dominated by contributions from the single diffractive dissociation process ($pp \to Xp$), enhanced by double dissociation ($pp \to XY$) where the invariant mass of the lighter of the two dissociation systems satisfies $M_Y \lesssim 7\;\text{GeV}$. The resulting cross section is $\mathrm{d} \sigma / \mathrm{d} \Delta \eta_F \sim 1$ mb for $\Delta \eta_F \gtrsim 3$. The large rapidity gap data are used to constrain the value of the pomeron intercept appropriate to triple Regge models of soft diffraction. The cross section integrated over all gap sizes is compared with other LHC inelastic cross section measurements.

Inclusive jet and dijet cross sections at 7 TeV (ATLAS_2012_I1082936)

Inspire | HepData | arXiv:1112.6297v2 [hep-ex] | CERN-PH-EP-2011-192

Inclusive jet and dijet cross sections have been measured in proton-proton collisions at a centre-of-mass energy of 7 TeV using the ATLAS detector at the Large Hadron Collider. The cross sections were measured using jets clustered with the anti-kT algorithm with parameters R=0.4 and R=0.6. These measurements are based on the 2010 data sample, consisting of a total integrated luminosity of 37 inverse picobarns. Inclusive jet double-differential cross sections are presented as a function of jet transverse momentum, in bins of jet rapidity. Dijet double-differential cross sections are studied as a function of the dijet invariant mass, in bins of half the rapidity separation of the two leading jets. The measurements are performed in the jet rapidity range $|y|<4.4$, covering jet transverse momenta from 20 GeV to 1.5 TeV and dijet invariant masses from 70 GeV to 5 TeV. This is the successor analysis of ATLAS_2010_S8817804

$D^{*\pm}$ production in jets (ATLAS_2012_I1082009)

Inspire | HepData | arXiv:1112.4432

Measurement of $D^{*\pm}$ meson production in jets from proton-proton collisions at a centre-of-mass energy of $\sqrt{s}=7$ TeV at the LHC. The measurement is based on a data sample recorded with the ATLAS detector with an integrated luminosity of $0.30\,\text{pb}^{-1}$ for jets with transverse momentum between 25 and 70 GeV in the pseudorapidity range $|eta| < 2.5$.

$K_S^0$ and $\Lambda$ production at 0.9 and 7 TeV with ATLAS (ATLAS_2011_I944826)

Inspire | HepData | arXiv:1111.1297v2 [hep-ex] | Phys.Rev. D85 (2012) 012001

The production of $K_S$ and $\Lambda$ hadrons is studied in inelastic $pp$ collisions at $\sqrt{s} = 0.9$ and 7 TeV collected with the ATLAS detector at the LHC using a minimum-bias trigger. The observed distributions of transverse momentum, rapidity, and multiplicity are corrected to hadron level in a model-independent way within well defined phase-space regions. The distribution of the production ratio of $\bar{\Lambda}$ to $\Lambda$ baryons is also measured. The results are compared with various Monte Carlo simulation models. Although most of these models agree with data to within 15 percent in the $K_S$ distributions, substantial disagreements with data are found in the $\Lambda$ distributions of transverse momentum.

Inclusive and dijet cross-sections of $b$-jets in $pp$ collisions at $\sqrt{s} = 7$ TeV with ATLAS (ATLAS_2011_I930220)

Inspire | HepData | Eur.Phys.J. C71 (2011) 1846 | arXiv:1109.6833 [hep-ex]

The inclusive and dijet production cross-sections have been measured for jets containing $b$-hadrons ($b$-jets) in proton--proton collisions at a centre-of-mass energy of $\sqrt{s} = 7$ TeV, using the ATLAS detector at the LHC. The measurements use data corresponding to an integrated luminosity of 34 pb$^-1$. The $b$-jets are identified using either a lifetime-based method, where secondary decay vertices of $b$-hadrons in jets are reconstructed using information from the tracking detectors, or a muon-based method where the presence of a muon is used to identify semileptonic decays of $b$-hadrons inside jets. The inclusive $b$-jet cross-section is measured as a function of transverse momentum in the range $20 < pT < 400$ GeV and rapidity in the range $|y| < 2.1$. The $b\bar{b}$-dijet cross-section is measured as a function of the dijet invariant mass in the range $110 < $m_{jj}$ < 760$\;GeV, the azimuthal angle difference between the two jets and the angular variable $\chi$ in two dijet mass regions. The results are compared with next-to-leading-order QCD predictions. Good agreement is observed between the measured cross-sections and the predictions obtained using POWHEG+Pythia6. MC@NLO+Herwig shows good agreement with the measured $b\bar{b}$-dijet cross-section. However, it does not reproduce the measured inclusive cross-section well, particularly for central $b$-jets with large transverse momenta.

Jet fragmentation at 7 TeV (ATLAS_2011_I929691)

Inspire | HepData | Eur.Phys.J.C 71 (2011) 1795 | doi:10.1140/epjc/s10052-011-1795-y | arXiv:1109.5816 [hep-ex]

The jet fragmentation function and transverse profile for jets with 25 GeV $< p_\text{T jet} < 500$ GeV and $|\eta_\text{jet}| < 1.2$ produced in proton-proton collisions with a center-of-mass energy of 7 TeV are presented. The measurement is performed using data with an integrated luminosity of 36 pb${}^{-1}$. Jets are reconstructed and their momentum measured using calorimetric information. The momenta of the charged particle constituents are measured using the tracking system. The distributions corrected for detector effects are compared with various Monte Carlo event generators and generator tunes. Several of these choices show good agreement with the measured fragmentation function. None of these choices reproduce both the transverse profile and fragmentation function over the full kinematic range of the measurement.

Measurement of electron and muon differential cross-section from heavy-flavour decays (ATLAS_2011_I926145)

Inspire | HepData | CERN-PH-EP-2011-108 | arXiv:1109.0525 [hep-ex]

Measurement of inclusive electron and muon cross sections for $7 < p_\perp <26$ GeV in $|\eta| <2.0$, excluding $1.37<|\eta|<1.52$, and muon cross section for $4 < p_\perp < 100$ GeV in $|\eta| <2.50$. The $W/Z/\gamma^*$ component must be subtracted to leave the heavy flavour contribution.

Measurement of ATLAS track jet properties at 7 TeV (ATLAS_2011_I919017)

Inspire | HepData | Phys.Rev.D 84 (2011) 054001 | doi:10.1103/PhysRevD.84.054001 | arXiv:1107.3311 | ATLAS-STDM-2010-14 | CERN-PH-EP-2011-110

ATLAS measurement of track jet pT, multiplicity per jet, longitudinal fragmentation, transverse momentum, radius w.r.t jet axis distributions, with jets constructed from charged tracks with $pT > 300$ MeV, using the anti-$k_T$ jet algorithm with $R = 0.4, 0.6$.

Measurement of the inelastic proton-proton cross-section at $\sqrt{s} = $7 TeV. (ATLAS_2011_I894867)

Inspire | HepData | arXiv:1104.0326 [hep-ex]

Inelastic cross-section is measured for $\xi > 5 \times 10^{-6}$, where $\xi=M_X^2/s$ is calculated from the invariant mass, $M_X$, of hadrons selected using the largest rapidity gap in the event.

Measurement of multi-jet cross sections (ATLAS_2011_S9128077)

Inspire | HepData | arXiv:1107.2092

Inclusive multi-jet production is studied using an integrated luminosity of 2.4 pb-1. Results on multi-jet cross sections are presented differential in pT of the four leading jets, HT. Additionally three-to-two jet fractions are presented differential in different observables. Jets are anti-$k_t$ with $R=0.4$ and $R=0.6$, $p_\perp>80(60)$ GeV and $|\eta|<2.8$.

Measurement of dijet production with a veto on additional central jet activity (ATLAS_2011_S9126244)

Inspire | HepData | arXiv:1107.1641 [hep-ex]

A measurement of the jet activity in rapidity intervals bounded by a dijet system. The fraction of events passing a veto requirement are shown as a function of both the rapidity interval size and the average transverse momentum of the dijet system. The average number of jets above the veto threshold are also shown as a function of the same variables. There are two possible selection criteria applied to data. Either the two highest transverse momentum jets or the jets most forward and backward in rapidity are taken to define the dijet system, where the veto threhsold is 20\;GeV. Additionally for the latter selection an alternative veto transverse momentum threshold which is equal to the average transverse momentum is applied. Jet selections are based on the anti-$k_t$ algorithm with $R=0.6$, $p_\perp > 20$\;GeV and $|y_\text{jet}| < 4.4$.

Measurement of J/Psi production (ATLAS_2011_S9035664)

Inspire | HepData | arXiv:1104.3038 [hep-ex]

The inclusive $J/\psi$ production cross-section and fraction of $J/\psi$ mesons produced in B-hadron decays are measured in proton-proton collisions at $\sqrt{s} = 7$ TeV with the ATLAS detector at the LHC, as a function of the transverse momentum and rapidity of the J/psi, using 2.3$\textrm{pb}^{-1}$ of integrated luminosity. The cross section is measured from a minimum $p_T$ of 1 GeV to a maximum of 70 GeV and for rapidities within $|y| < 2.4$ giving the widest reach of any measurement of $J/\psi$ production to date.

Calo-based underlying event at 900 GeV and 7 TeV in ATLAS (ATLAS_2011_S8994773)

Inspire | HepData | arXiv:1103.1816

Underlying event measurements with the ATLAS detector at the LHC at center-of-mass energies of 900 GeV and 7 TeV, using calorimeter clusters rather than charged tracks.

Dijet azimuthal decorrelations (ATLAS_2011_S8971293)

Inspire | HepData | arXiv:1102.2696

Dijet azimuthal decorrelation measured by ATLAS at 7 TeV. Jets are anti-$k_t$ with $R = 0.6$, $p_\perp > 100$\;GeV, $|\eta| < 0.8$. The analysis is binned in leading jet $p_\perp$ bins. All data is fully corrected for detector effects.

Jet shapes at 7 TeV in ATLAS (ATLAS_2011_S8924791)

Inspire | HepData | arXiv:1101.0070

Measurement of jet shapes in inclusive jet production in $pp$ collisions at 7 TeV based on 3 pb$^{-1}$ of data. Jets are reconstructed in $|\eta| < 5$ using the anti-$k_\perp$ algorithm with $30 < p_\perp < 600$ GeV and $|y| < 2.8$.

Cross-section and fragmentation function in anti-$k_t$ track jets (ATLAS_2010_CONF_2010_049)

Inspire | HepData | ATLAS-CONF-2010-049

Jets are identified and their properties studied using tracks measured by the ATLAS Inner Detector. Events are selected using a minimum-bias trigger, allowing the emergence of jets at low transverse momentum to be observed and for jets to be studied independently of the calorimeter. Jets are reconstructed using the anti-kt algorithm applied to tracks with two parameter choices, 0.4 and 0.6. An inclusive jet transverse momentum cross section measurement from 4 GeV to 80 GeV is shown, integrated over $|\eta| < 0.57$ and corrected to charged particle-level truth jets. The probability that a particular particle carries a fixed fraction of the jet momentum (fragmentation function) is also measured. All data is corrected to the particle level. ATTENTION - Data read from plots!

Track-based minimum bias at 900 GeV and 2.36 and 7 TeV in ATLAS (ATLAS_2010_S8918562)

Inspire | HepData | arXiv:1012.5104

Measurements from proton-proton collisions at centre-of-mass energies of $\sqrt{s} = 0.9$, 2.36, and 7 TeV recorded with the ATLAS detector at the LHC. Events were collected using a single-arm minimum-bias trigger. The charged-particle multiplicity, its dependence on transverse momentum and pseudorapidity and the relationship between the mean transverse momentum and charged-particle multiplicity are measured. Measurements in different regions of phase-space are shown, providing diffraction-reduced measurements as well as more inclusive ones. The observed distributions are corrected to well-defined phase-space regions, using model-independent corrections.

Track-based underlying event at 900 GeV and 7 TeV in ATLAS (ATLAS_2010_S8894728)

Inspire | HepData | arXiv:1012.0791

The underlying event measurements with the ATLAS detector at the LHC at the center of mass energies of 900 GeV and 7 TeV. The observables sensitive to the underlying event, i.e the charged particle density and charged pT sum, as well as their standard deviations and the average pT, are measured as functions of the leading track. A track pT cut of 500 MeV is applied for most observables, but the main profile plots are also shown for a lower track cut of 100 MeV, which includes much more of the soft cross-section. The angular distribution of the charged tracks with respect to the leading track is also studied, as are the correlation between mean transverse momentum and charged particle multiplicity, and the `plateau' height as a function of the leading track $|\eta|$.

Inclusive jet cross section and di-jet mass and chi spectra at 7 TeV in ATLAS (ATLAS_2010_S8817804)

Inspire | HepData | arXiv:1009.5908

The first jet cross section measurement made with the ATLAS detector at the LHC. Anti-kt jets with $R=0.4$ and $R=0.6$ are resconstructed within $|y|<2.8$ and above 60 GeV for the inclusive jet cross section plots. For the di-jet plots the second jet must have pT>30 GeV. Jet pT and di-jet mass spectra are plotted in bins of rapidity between $|y| = $ 0.3, 0.8, 1.2, 2.1, and 2.8. Di-jet $\chi$ spectra are plotted in bins of di-jet mass between 340 GeV, 520 GeV, 800 GeV and 1200 GeV.

Charged particles at 900 GeV in ATLAS (ATLAS_2010_S8591806)

Inspire | HepData | arXiv:1003.3124

The first measurements with the ATLAS detector at the LHC. Data were collected using a minimum-bias trigger in December 2009 during proton-proton collisions at a centre of mass energy of 900 GeV. The charged- particle density, its dependence on transverse momentum and pseudorapid- ity, and the relationship between transverse momentum and charged-particle multiplicity are measured for events with at least one charged particle in the kinematic range $|\eta| < 2.5$ and $p_\perp > 500$ MeV. All data is corrected to the particle level.

Measurement of jet substructure observables in $t\bar{t}$ events from $pp$ collisions at 13 TeV (CMS_2018_I1690148)

Inspire | HepData | arXiv:1808.07340 | CMS-TOP-17-013 | Phys. Rev. D 98, 092014 (2018)

A measurement of jet substructure observables is presented using $t\bar{t}$ events in the lepton+jets channel from proton-proton collisions at $\sqrt{s}=13$ TeV recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of 35.9/fb. Multiple jet substructure observables are measured for jets identified as bottom, light-quark, and gluon jets, as well as for inclusive jets (no flavor information). The results are unfolded to the particle level and compared to next-to-leading-order predictions from POWHEG interfaced with the parton shower generators PYTHIA 8 and HERWIG 7, as well as from SHERPA 2 and DIRE 2. A value of the strong coupling at the Z boson mass, $\alpha_{S}(m_{Z}) = 0.115^{+0.015}_{-0.013}$, is extracted from the substructure data at leading-order plus leading-log accuracy.

Jet mass in dijet events in $pp$ collisions at 13 TeV (CMS_2018_I1682495)

Inspire | HepData | JHEP 11 (2018) 113 | DOI 10.1007/JHEP11(2018)113 | hep-ex arXiv:1807.05974 | inspirehep 1682495 | http://cms-results.web.cern.ch/cms-results/public-results/publications/SMP-16-010/index.html

Measurements of the differential jet cross section are presented as a function of jet mass in dijet events, in bins of jet transverse momentum, with and without a jet grooming algorithm. The data have been recorded by the CMS Collaboration in proton-proton collisions at the LHC at a center-of-mass energy of 13\text{TeV} and correspond to an integrated luminosity of 2.3\fbinv. The absolute cross sections show slightly different jet transverse momentum spectra in data and Monte Carlo event generators for the settings used. Removing this transverse momentum dependence, the normalized cross section for ungroomed jets is consistent with the prediction from Monte Carlo event generators for masses below 30\% of the transverse momentum. The normalized cross section for groomed jets is measured with higher precision than the ungroomed cross section. Semi-analytical calculations of the jet mass beyond leading logarithmic accuracy are compared to data, as well as predictions at leading order and next-to-leading order, which include parton showering and hadronization. Overall, in the normalized cross section, the theoretical predictions agree with the measured cross sections within the uncertainties for masses from 10 to 30\% of the jet transverse momentum.

Charged particle distributions in different final states at 13 TeV (CMS_2018_I1680318)

Inspire | HepData | Eur.Phys.J. C78 (2018) no.9, 697 | DOI: 10.1140/epjc/s10052-018-6144-y | arXiv:1806.11245 [hep-ex] | http://cms-results.web.cern.ch/cms-results/public-results/publications/FSQ-16-011/

Charged particle distributions in different final states at $\sqrt{s} = 13$ TeV by the CMS experiment. Pseudorapidity, multiplicity and transverse momentum distributions of all charged particles. Also the $p_\perp$ leading charged particle spectrum and its integration as function of $p_\perp$. The distributions are presented for inelastic, non-single-diffractive and single-diffractive event selections. Please note, that the MC predictions are not scaled to the datapoints, in contrast to Figure 6 in the publication.

Differential cross sections for top quark pair production using the lepton+jets final state in proton proton collisions at 13 TeV (CMS_2018_I1663958)

Inspire | HepData | arXiv:1803.08856 | CMS-TOP-17-002 | Submitted to Phys. Rev. D.

Abstract: Differential and double-differential cross sections for the production of top quark pairs in proton-proton collisions at $\sqrt{s} = 13$\,TeV are measured as a function of kinematic variables of the top quarks and the top quark-antiquark ($\text{t}\bar{\text{t}}$) system. In addition, kinematic variables and multiplicities of jets associated with the $\text{t}\bar{\text{t}}$ production are measured. This analysis is based on data collected by the CMS experiment at the LHC in 2016 corresponding to an integrated luminosity of 35.8\,fb$^{-1}$. The measurements are performed in the lepton+jets decay channels with a single muon or electron and jets in the final state. The differential cross sections are presented at the particle level, within a phase space close to the experimental acceptance, and at the parton level in the full phase space. The results are compared to several standard model predictions that use different methods and approximations. The kinematic variables of the top quarks and the $\text{t}\bar{\text{t}}$ system are reasonably described in general, though none predict all the measured distributions. In particular, the transverse momentum distribution of the top quarks is more steeply falling than predicted. The kinematic distributions and multiplicities of jets are adequately modeled by certain combinations of next-to-leading-order calculations and parton shower models. Rivet: This analysis is to be run on $\text{t}\bar{\text{t}}$ Monte Carlo. The particle-level phase space is defined using the following definitions: \begin{description} \item[lepton]: an electron or muon with $p_\text{T}>30\,\text{GeV}$ and $|\eta|<2.4$, dressed within a cone of radius 0.1, \item[jet]: a jet is reconstructed with the anti-$k_\text{T}$ algorithm with a radius of 0.4, after removing the neutrinos and dressed leptons, with $p_\text{T]>25\,\text{GeV}$ and $|\eta|<2.4$, \item[b-jet]: a jet that contains a B-hadron. \end{description} A W boson is reconstructed from a lepton and the sum of the neutrino energies, while another W boson is reconstructed from a light jet pair. The two top quarks are reconstructed by combining b jets to these W boson. A check based on the W boson and top quark masses is performed to choose the proper combinations.

Measurement of the differential cross sections of top quark pair production as a function of kinematic event variables in pp collisions at sqrt(s) = 13 TeV (CMS_2018_I1662081)

Inspire | HepData | TOP-16-014 | arxiv:1803.03991 | Submitted to JHEP

Abstract : Measurements of the differential $\mathrm{t}\overline{\mathrm{t}}$ production cross section are presented in the single-lepton decay channel, with respect to a number of global event observables. The measurements are performed with $\text{35.9 fb}^{-1}$ of proton-proton collision data collected by the CMS experiment at the LHC during 2016 at $\sqrt{s} = \text{13 TeV}$. The differential cross sections are measured at the level of long-lived generated particles in a phase space similar to that accessible by the CMS detector, and are compared to state-of-the-art leading-order and next-to-leading-order $\mathrm{t}\overline{\mathrm{t}}$ simulations. Rivet : This analysis is to be run on ${\rm t\bar{t}}$ simulation. The particle level selection requires: - exactly one electron or muon with $p_{T} > 26$ GeV and $|\eta| < 2.4$ - no additional electrons or muons with $p_{T} > 15$ GeV and $|\eta| < 2.4$ - at least thress jets with $p_{T} > 30$ GeV and $|\eta| < 2.4$, and one jet with $p_{T} > 25$ GeV and $|\eta| < 2.4$ - two of these selected jets must be tagged as originating from a b quark.

Measurement of the inelastic proton-proton cross section at 13 TeV (CMS_2018_I1653948)

Inspire | HepData | JHEP 07 (2018) 161 | DOI 10.1007/JHEP07(2018)161 | CMS-FSQ-15-005 | arXiv:1802.02613 [hep-ex] | CERN-EP-2018-004 | http://cms-results.web.cern.ch/cms-results/public-results/publications/FSQ-15-005/

A measurement of the inelastic proton-proton cross section at $\sqrt{s} = 13$ TeV with the CMS detector at the LHC has been presented. An inelastic cross section of $67.5 \pm 0.8 \text{(syst)} \pm 1.6 \text{(lumi)}$ mb is obtained for $\xi = M^2/s > 10^{-6}$ (corresponding to $M > 13$ GeV), with $M$ the larger of $M_{\mathrm{X}}$ and $M_{\mathrm{Y}}$, where $M_{\mathrm{X}}$ and $M_{\mathrm{Y}}$ are the masses of the diffractive dissociation systems with negative and positive pseudorapidities, respectively. In addition, an inelastic cross section of $68.6 \pm 0.5 \text{(syst)} \pm 1.6 \text{(lumi)}$ mb is obtained in the enlarged phase space $\xi_{\mathrm{X}} > 10^{-7}$ and/or $\xi_{\mathrm{Y}} > 10^{-6}$ (corresponding to $M_{\mathrm{X}} > 4.1$ GeV and/or $M_{\mathrm{Y}} > 13$ GeV).

Measurements of jet charge with dijet events in pp collisions at $\sqrt{s}=8$ TeV (CMS_2017_I1605749)

Inspire | HepData | DOI:10.1007/JHEP10(2017)131 | arXiv:1706.05868 | CMS-SMP-15-003

Jet charge is an estimator of the electric charge of a quark, antiquark, or gluon initiating a jet. It is based on the momentum-weighted sum of the electric charges of the jet constituents. Measurements of three charge observables of the leading jet in transverse momentum $p_\mathrm{T}$ are performed with dijet events. The analysis is carried out with data collected by the CMS experiment at the CERN LHC in proton-proton collisions at $\sqrt{s}=8\text{TeV}$ corresponding to an integrated luminosity of 19.7 fb$^{-1}$. The results are presented in bins of the $p_\mathrm{T}$ of the leading jet.

Differential $t\bar{t}$ production cross-section as a function of the leading jet mass for boosted top quarks at 8 TeV (CMS_2017_I1518399)

Inspire | HepData | TOP-15-015 | arXiv:1703.06330 | Submitted to Eur. Phys. J. C.

Measurement of the differential and normalised differential $t\bar{t}$ production cross section as a function of the leading jet mass. The measurement was performed in the lepton+jets channel and the fiducial measurement phase space is enriched with events where the leading jet includes all decay products of a hadronically decaying top quark. This analysis is to be run on ${t\bar{t}}$ simulation. The objects are defined as follows - Lepton: electron or muon originating from the decay of a W boson - Jets: jets are clustered from final state particles using the Cambridge-Aachen algorithm with a distance parameter of 1.2. If a lepton overlaps with a jet (distance in the eta-phi plane smaller 1.2) its four momentum is subtracted from the four momentum of the jet. Definition of the particle level phase space: - only ${\rm t\bar{t}}$ decays with one top quark decaying hadronically and one top quark decaying leptonically including an electron or muon from the W decay. - lepton $\pt > 45\;\text{GeV}$ and $|\eta| < 2.1$ - at least one jet with $\pt > 400\;\text{GeV}$ and $|\eta| < 2.5$ - a second jet with $\pt > 150\;\text{GeV}$ and $|\eta| < 2.5$ - veto on additional jets with $\pt > 150\;\text{GeV}$ and $|\eta| < 2.5$ - distance between the second jet and the lepton in the eta-phi plane $\Delta R(jet2, lepton)$ smaller 1.2 - invariant mass of the leading jet larger than the invariant mass of the combination of the second jet and lepton The differential and normalised differential cross section was measured as a function of the leading jet mass.

Measurement of the inclusive energy spectrum in the very forward direction in proton-proton collisions at 13 TeV (CMS_2017_I1511284)

Inspire | HepData

The differential cross section for inclusive particle production as a function of energy in proton-proton collisions at a center-of-mass energy of 13 TeV is measured in the very forward region of the CMS detector. The measurement is based on data collected with the CMS apparatus at the LHC, and corresponds to an integrated luminosity of 0.35 inverse microbarns. The energy is measured in the CASTOR calorimeter, which covers the pseudorapidity region $-6.6 < \eta < -5.2$. The results are given as a function of the total energy deposited in CASTOR, as well as of its electromagnetic and hadronic components. The spectra are sensitive to the modeling of multiparton interactions in pp collisions, and provide new constraints for hadronic interaction models used in collider and in high energy cosmic ray physics.

Two- and multi-particle angular correlations in pp collisions at $\sqrt{s} = 13$ TeV. (CMS_2017_I1471287)

Inspire | HepData | Phys.Lett. B765 (2017) 193-220 | DOI:10.1016/j.physletb.2016.12.009 | arXiv:1606.06198

Measurement of two- and multi-particle angular correlations of charged particles as well as $K^0_s$ and $\Lambda + \bar{\Lambda}$. Measurements are done $p_\perp$ integrated as function of event multiplicity, and $p_\perp$ differential in two bins of event multiplicity; high and low. The experimental analysis performs also a subtraction procedure of low multiplicity results from high multiplicity ones. Such a subtraction is not performed in the RIVET analysis (due to the difficulty of performing the same procedure on MC), and as such, only unsubtracted values are used. Bin edges for integrated correlations are not reported in HepData, and are as such based simply on midpoints between reported points.

Differential cross sections for top quark pair production using the lepton+jets final state in proton proton collisions at 13 TeV (CMS_2016_I1491950)

Inspire | HepData | Phys. Rev. D 95 (2017) 092001 | arXiv:1610.04191 | CMS-TOP-16-008

Abstract: Differential and double-differential cross sections for the production of top quark pairs in proton-proton collisions at 13 TeV are measured as a function of jet multiplicity and of kinematic variables of the top quarks and the top quark-antiquark system. This analysis is based on data collected by the CMS experiment at the LHC corresponding to an integrated luminosity of 2.3 inverse femtobarns. The measurements are performed in the lepton+jets decay channels with a single muon or electron in the final state. The differential cross sections are presented at particle level, within a phase space close to the experimental acceptance, and at parton level in the full phase space. The results are compared to several standard model predictions. Rivet: This analysis is to be run on $\text{t}\bar{\text{t}}$ Monte Carlo. The particle-level phase space is defined using the following definitions: an electron or muon with $p_\text{T}>30\,\text{GeV}$ and $|\eta|<2.5$, dressed within a cone of radius 0.1; a jet is reconstructed with the anti-$k_t$ algorithm with a radius of 0.4, after removing the neutrinos and dressed leptons, with $p_\text{T}>25\,\text{GeV}$ and $|\eta|<2.5$; a jet that contains a B-hadron. A W boson is reconstructed from a lepton and the sum of the neutrino energies, while another W boson is reconstructed from a light jet pair. The two top quarks are reconstructed by combining b jets to these W boson. A check based on the W boson and top quark masses is performed to choose the proper combinations.

Measurement and QCD analysis of double-differential inclusive jet cross sections in pp collisions at $\sqrt{s} = 8\;\text{TeV}$ and cross section ratios to 2.76 and 7 TeV (CMS_2016_I1487277)

Inspire | HepData | DOI:10.1007/JHEP03(2017)156 | arXiv:1609.05331 | CMS-SMP-14-001

A measurement of the double-differential inclusive jet cross section as a function of the jet transverse momentum $\pt$ and the absolute jet rapidity $\abs{y}$ is presented. Data from LHC proton-proton collisions at $\sqrt{s}=8\text{TeV}$, corresponding to an integrated luminosity of 19.7 fb^{-1}, have been collected with the CMS detector. Jets are reconstructed using the anti-$\kt$ clustering algorithm with a size parameter of 0.7 in a phase space region covering jet $\pt$ from $74\text{GeV}$ up to $2.5\text{TeV}$ and jet absolute rapidity up to $\abs{y}=3.0$. The low-$\pt$ jet range between 21 and $74\text{GeV}$ is also studied up to $\abs{y}=4.7$, using a dedicated data sample corresponding to an integrated luminosity of 5.6\pbinv. The measured jet cross section is corrected for detector effects and compared with the predictions from perturbative QCD at next-to-leading order (NLO) using various sets of parton distribution functions (PDF). Cross section ratios to the corresponding measurements performed at 2.76 and $7\text{TeV}$ are presented. From the measured double-differential jet cross section, the value of the strong coupling constant evaluated at the $\PZ$ mass is $\alpha_\mathrm{S}(M_{\PZ}) = 0.1164^{+0.0060}_{-0.0043}$, where the errors include the PDF, scale, nonperturbative effects and experimental uncertainties, using the CT10 NLO PDFs. Improved constraints on PDFs based on the inclusive jet cross section measurement are presented.

Studies of 2 $b$-jet + 2 jet production in proton-proton collisions at 7 TeV (CMS_2016_I1486238)

Inspire | HepData | CMS-FSQ-13-010 | CERN-EP-2016-191 | arXiv:1609.03489 | Phys.Rev. D94 (2016) no.11, 112005

Measurements are presented of the cross section for the production of at least four jets, of which at least two originate from $b$ quarks, in proton-proton collisions. Data collected with the CMS detector at the LHC at a center-of-mass energy of 7 TeV are used, corresponding to an integrated luminosity of 3 inverse picobarns. The cross section is measured as a function of the jet transverse momentum for p_\perp 20 GeV, and of the jet pseudorapidity for $|\eta|<2.4$ ($b$ jets) and 4.7 (untagged jets). The correlations in azimuthal angle and p_\perp between the jets are also studied. The $\eta$ and p_\perp distributions of the four jets and the correlations between them are well reproduced by event generators that combine perturbative QCD calculations at next-to-leading-order accuracy with contributions from parton showers and multiparton interactions.

Measurement of the differential cross sections for top quark pair production as a function of kinematic event variables at sqrt(s) = 8 TeV (CMS_2016_I1473674)

Inspire | HepData | arXiv:1607.00837

Measurements are reported of the normalized differential cross sections for top quark pair production with respect to four kinematic event variables: the missing transverse energy; the scalar sum of the jet transverse momentum (pT); the scalar sum of the pT of all objects in the event; and the pT of leptonically decaying W bosons from top quark decays.

Measurement of the inclusive jet cross-section in $pp$ collisions at $\sqrt{s} = 13\;\text{TeV}$ (CMS_2016_I1459051)

Inspire | HepData | Eur.Phys.J. C76 (2016) no.8, 451 | CERN-EP-2016-104 | CMS-SMP-15-007

A measurement of the double-differential inclusive jet cross section as a function of jet transverse momentum pT and absolute jet rapidity |y| is presented. The analysis is based on proton-proton collisions collected by the CMS experiment at the LHC at a centre-of-mass energy of 13 TeV. The data samples correspond to integrated luminosities of 71 and 44 pb-1 for |y| < 3 and 3.2 < |y| < 4.7, respectively. Jets are reconstructed with the anti-kt clustering algorithm for two jet sizes, R, of 0.7 and 0.4, in a phase space region covering jet pT up to 2 TeV and jet rapidity up to |y| = 4.7. Predictions of perturbative quantum chromodynamics at next-to-leading order precision, complemented with electroweak and nonperturbative corrections, are used to compute the absolute scale and the shape of the inclusive jet cross section. The cross-section difference in $R$, when going to a smaller jet size of 0.4, is best described by Monte Carlo event generators with next-to-leading order predictions matched to parton showering, hadronisation, and multiparton interactions. In the phase space accessible with the new data, this measurement provides a first indication that jet physics is as well understood at $\sqrt(s) = 13\;\text{TeV}$ as at smaller centre-of-mass energies.

Boosted $t\bar{t}$ in $pp$ collisions at $\sqrt{s} = 8 \text{TeV}$ (CMS_2016_I1454211)

Inspire | HepData | CMS-PAS-TOP-14-012 (PAS) | CERN-EP-2016-078 (paper)

The cross section for pair production of top quarks with high transverse momenta ($p_\mathrm{T} > 400$ \text{GeV}) is measured in 19.7 fb$^{-1}$ of $\mathrm{pp}$ collisions, collected with the CMS detector at $\sqrt{s} = 8 \text{TeV}$. The measurement is performed for lepton+jets events, where one top quark decays according to $t \rightarrow Wb \rightarrow \ell \nu b$, with $\ell$ denoting an electron or muon, and the second top quark decays to an hadronic final state and is reconstructed as a single large-radius jet and identified as a top quark candidate using jet substructure techniques. Integrated cross sections, as well as differential cross sections as a function of the top quark $p_\mathrm{T}$ and rapidity, are measured both at particle level within a fiducial region resembling the detector-level selections and at parton level. RIVET: This analysis is to be run on $t\bar{t}$ Monte Carlo. It utilizes the PartonicTops projection, which assumes top quarks in the event record. The analysis has been validated with Powheg+Pythia6. The parton-level phase space is defined by requiring two PartonicTops. Exactly one PartonicTop must decay directly to a muon or electron (no intermediate tau), and exactly one PartonicTop decays hadronically. For $t\bar{t}$ Monte Carlo, this is equivalent to requiring the event to be semileptonic at parton level. The parton-level top quark is defined as the hadronically decaying top. The parton-level top quark is required to have $p_\mathrm{T} > 400 \text{GeV}$. The particle-level phase space is defined using the following object definitions: - Lepton: A dressed electron or muon, meaning the lepton has been clustered with all photons within a cone of $R=0.1$. The DressedLepton projection is used to construct the dressed lepton. The lepton is required to have $p_\mathrm{T} > 45$ GeV and $|\eta| < 2.1$. - B Jet Candidate: Gen AK5 jets are formed by clustering the final state particles in the event using the anti-$k_{T}$ algorithm with distance parameter $R=0.5$. Neutrinos are excluded from the clustering, as are any particles included in the dressed lepton. The gen AK5 jet is required to have $p_{T} > 30$ GeV and $|\eta| < 2.4$. Gen AK5 jets in the same hemisphere as the lepton ($\Delta R(e/\mu, \mathrm{jet}) < \pi/2$) are defined as $b$-jet candidates. - Top Jet Candidate: Gen CA8 jets are formed by clustering the final state particles in the event using the Cambridge-Aachen algorithm with distance parameter $R=0.8$. Neutrinos are excluded from the clustering, as are any particles included in the dressed lepton. The gen CA8 jet is required to have $p_{T} > 30$ GeV and $|\eta| < 2.4$. Gen CA8 jets which have $p_{T} > 400$ GeV, 140 GeV $<$ mass $<$ 250 GeV, and are in the opposite hemisphere from the lepton ($\Delta{\rm R(e/\mu, jet)} > \pi/2$) are defined as top jet candidates. The particle-level phase space is defined by requiring $\geq 1$ b jet candidate, $\geq 1$ top jet candidate, and exactly one lepton. This is in addition to the parton-level semileptonic requirement. The highest-$p_\mathrm{T}$ top jet candidate is defined as the particle-level $t$ jet.

Measurements of ttbar charge asymmetry using dilepton final states in pp collisions at sqrt(s) = 8 TeV (CMS_2016_I1430892)

Inspire | HepData | Phys. Lett. B 760 (2016) 365 | DOI:10.1016/j.physletb.2016.07.006 | arXiv:1603.06221 | https://hepdata.net/record/ins1430892

$\textbf{Abstract:}$ The charge asymmetry in $\mathrm{t\bar{t}}$ events is measured using dilepton final states produced in pp collisions at the LHC at $\sqrt{s}=8\:$TeV. The data sample, collected with the CMS detector, corresponds to an integrated luminosity of 19.5 $\mathrm{fb^{-1}}$. The measurements are performed using events with two oppositely charged leptons (electrons or muons) and two or more jets, where at least one of the jets is identified as originating from a bottom quark. The charge asymmetry is measured from differences in kinematic distributions, unfolded to the parton level, of positively and negatively charged top quarks and leptons. The $\mathrm{t\bar{t}}$ and leptonic charge asymmetries are found to be 0.011 +/- 0.011 (stat) +/- 0.007 (syst) and 0.003 +/- 0.006 (stat) +/- 0.003 (syst), respectively. These results, as well as charge asymmetry measurements made as a function of $\mathrm{t\bar{t}}$ system kinematic properties, are in agreement with predictions of the standard model. $\textbf{Particle-level addition to Rivet routine:}$ While the analysis was performed at the parton-level only, $\Delta|\eta_{\ell}|$ is a purely leptonic variable and it has been checked that the results of the analysis would have been essentially unchanged had it been defined at particle-level using dressed leptons instead of using the parton-level top quark daughter leptons. We therefore include both particle- and parton-level versions of this distribution in the Rivet routine, with the former identified in the plot title. For same-flavour dilepton final states, the particle-level definition in the full phase space is problematic because the two leptons can come from fully-hadronic $\mathrm{t\bar{t}}$ plus a dilepton pair from radiation. Such pairs have invariant mass $M_{\ell\ell}\sim 0$ and produce a peak near zero in the $\Delta|\eta_{\ell}|$ distribution. We therefore select only the $\mathrm{t\bar{t}}\to e\mu$ final state, by requiring exactly one electron and exactly one muon. Note this means $\mathrm{t\bar{t}}\to e\mu$ events with additional dilepton pairs from radiation are vetoed. For PYTHIA8 this amounts to 0.5% of $\mathrm{t\bar{t}}\to e\mu$ events - well below the level of sensitivity of the measured distribution. $\textbf{Histograms and covariance matrices:}$ The error bars in the measured distributions should not be used for fitting because there are significant correlations between bins. The covariance matrices for the statistical and systematic uncertainties in each distribution can be found in hepdata. The single-differential cross sections in hepdata are normalised to unit area (i.e. the integral is equal to one), while the double-differential cross sections in hepdata are normalised to the sum of entries (such that the sum of all bin heights is equal to one). This should be taken into account when comparing the measured distributions to the Rivet results and when using the covariance matrices. $\textbf{Underflow and overflow bins:}$ The lower and upper $\Delta|y_\mathrm{t}|$ and $\Delta|\eta_{\ell}|$ bins (starting and ending at -2 and +2, respectively) contain underflow and overflow events, i.e. the complete distribution from -infinity to +infinity is covered. Similarly, the upper $M_\mathrm{t\bar{t}}$, $p_\mathrm{T}^\mathrm{t\bar{t}}$, and $\left|y_\mathrm{t\bar{t}}\right|$ bins contain overflow events up to +infinity.

Dijet azimuthal decorrelations in $pp$ collisions at $\sqrt{s} = 8$ TeV (CMS_2016_I1421646)

Inspire | HepData | arXiv:1602.04384 [hep-ex] | CERN-PH-EP-2016-013

A measurement of the decorrelation of azimuthal angles between the two jets with the largest transverse momenta is presented for seven regions of leading jet transverse momentum up to 2.2 TeV. The analysis is based on the proton-proton collision data collected with the CMS experiment at a centre-of-mass energy of 8 TeV corresponding to an integrated luminosity of 19.7/fb. The dijet azimuthal decorrelation is caused by the radiation of additional jets and probes the dynamics of multijet production. The results are compared to fixed-order predictions of perturbative quantum chromodynamics (QCD), and to simulations using Monte Carlo event generators that include parton showers, hadronization, and multiparton interactions. Event generators with only two outgoing high transverse momentum partons fail to describe the measurement, even when supplemented with next-to-leading-order QCD corrections and parton showers. Much better agreement is achieved when at least three outgoing partons are complemented through either next-to-leading-order predictions or parton showers. This observation emphasizes the need to improve predictions for multijet production.

Measurements of ttbar spin correlations and top quark polarization using dilepton final states in pp collisions at sqrt(s) = 8 TeV (CMS_2016_I1413748)

Inspire | HepData | Phys. Rev. D 93, 052007 (2016) | DOI:10.1103/PhysRevD.93.052007 | arXiv:1601.01107 | https://hepdata.net/record/ins1413748

$\textbf{Abstract:}$ Measurements of the top quark-antiquark ($\mathrm{t\bar{t}}$) spin correlations and the top quark polarization are presented for $\mathrm{t\bar{t}}$ pairs produced in pp collisions at $\sqrt{s}=8\:$TeV. The data correspond to an integrated luminosity of 19.5 $\mathrm{fb^{-1}}$ collected with the CMS detector at the LHC. The measurements are performed using events with two oppositely charged leptons (electrons or muons) and two or more jets, where at least one of the jets is identified as originating from a bottom quark. The spin correlations and polarization are measured from the angular distributions of the two selected leptons, both inclusively and differentially, with respect to the invariant mass, rapidity, and transverse momentum of the $\mathrm{t\bar{t}}$ system. The measurements are unfolded to the parton level and found to be in agreement with predictions of the standard model. A search for new physics in the form of anomalous top quark chromo moments is performed. No evidence of new physics is observed, and exclusion limits on the real part of the chromo-magnetic dipole moment and the imaginary part of the chromo-electric dipole moment are evaluated. $\textbf{Particle-level addition to Rivet routine:}$ While the analysis was performed at the parton-level only, $\left|\Delta \phi_{\ell^+\ell^-}\right|$ is a purely leptonic variable and it has been checked that the results of the analysis would have been essentially unchanged had it been defined at particle-level using dressed leptons instead of using the parton-level top quark daughter leptons. We therefore include both particle- and parton-level versions of this distribution in the Rivet routine, with the former identified in the plot title. For same-flavour dilepton final states, the particle-level definition in the full phase space is problematic because the two leptons can come from fully-hadronic $\mathrm{t\bar{t}}$ plus a dilepton pair from radiation. Such pairs have invariant mass $M_{\ell\ell}\sim 0$ and produce a peak near zero in the $\left|\Delta \phi_{\ell^+\ell^-}\right|$ distribution. We therefore select only the $\mathrm{t\bar{t}}\to e\mu$ final state, by requiring exactly one electron and exactly one muon. Note this means $\mathrm{t\bar{t}}\to e\mu$ events with additional dilepton pairs from radiation are vetoed. For PYTHIA8 this amounts to 0.5% of $\mathrm{t\bar{t}}\to e\mu$ events - well below the level of sensitivity of the measured distribution. $\textbf{Histograms and covariance matrices:}$ The error bars in the measured distributions should not be used for fitting because there are significant correlations between bins. The covariance matrices for the statistical and systematic uncertainties in each distribution can be found in hepdata. The single-differential cross sections in hepdata are normalised to unit area (i.e. the integral is equal to one), while the double-differential cross sections in hepdata are normalised to the sum of entries (such that the sum of all bin heights is equal to one). This should be taken into account when comparing the measured distributions to the Rivet results and when using the covariance matrices. $\textbf{Overflow bins:}$ The upper $M_\mathrm{t\bar{t}}$, $p_\mathrm{T}^\mathrm{t\bar{t}}$, and $\left|y_\mathrm{t\bar{t}}\right|$ bins contain overflow events up to infinity.

Measurement of ttbar production with additional jet activity, including b quark jets, in the dilepton decay channel using pp collisions at sqrt(s)=8 TeV (CMS_2015_I1397174)

Inspire | HepData | arXiv:1510.03072

Jet multiplicity distributions in top quark pair ($t\bar{t}$) events are measured in $pp$ collisions at a centre-of-mass energy of 8\;\text{TeV} with the CMS detector at the LHC, using a data set corresponding to an integrated luminosity of 19.7/fb. The measurement is performed in the dilepton decay channels $e^+e^-$, $\mu^+\mu^-$, and $e^\pm\mu^\mp$). The absolute and normalized differential cross-sections for $t\bar{t}$ production are measured as a function of jet multiplicity for different jet transverse momentum thresholds and the kinematic properties of the leading additional jets. The differential $t\bar{t}b$ and $t\bar{t}b\bar{b}$ cross-sections are presented for the first time as a function of the kinematic properties of the leading additional $b$-jets. Furthermore, the fraction of events without additional jets above a threshold is measured as a function of the transverse momenta of the leading additional jets and the scalar sum of the transverse momenta of all additional jets.

Underlying event measurement with leading jets at $\sqrt{s} = 2.76$ \text{TeV} (CMS_2015_I1385107)

Inspire | HepData

A measurement of the underlying event (UE) activity in proton-proton collisions is performed using events with charged-particle jets produced in the central pseudorapidity region ($|\eta|^\text{jet} < 2$) and with transverse momentum $1 \leq p_T^\text{jet} < 100$ \text{GeV}. The analysis uses a data sample collected at a centre-of-mass energy of 2.76 \text{TeV} with the CMS experiment at the LHC. The UE activity is measured as a function of $p_T^\text{jet}$ in terms of the average multiplicity and scalar sum of transverse momenta of charged particles, with $|\eta| < 2$ and $p_T > 0.5$ \text{GeV}, in the azimuthal region transverse to the highest-$p_T$ jet direction. By further dividing the transverse region into two regions of smaller and larger activity, various components of the UE activity are separated.

Pseudorapidity distribution of charged hadrons in proton--proton collisions at $\sqrt{s} = 13$ TeV (CMS_2015_I1384119)

Inspire | HepData | arXiv:hep-ex/1507.05915

The pseudorapidity distribution of charged hadrons in $pp$ collisions at $\sqrt{s} =13$ TeV is measured using a data sample obtained with the CMS detector, operated at zero magnetic field, at the CERN LHC. The yield of primary charged long-lived hadrons produced in inelastic $pp$ collisions is determined in the central region of the CMS pixel detector ($|eta| < 2$) using both hit pairs and reconstructed tracks.

Per-event yield of the highest transverse momentum charged particle and charged-particle jet (CMS_2015_I1380605)

Inspire | HepData | arXiv:1507.00233

The per-event yield of the highest transverse momentum charged particle and charged-particle jet, integrated above a given $p_{T\;min}$ threshold starting at $p_{T\;min}=0.8$ and $1$ GeV, respectively, is studied in $pp$ collisions at $\sqrt{s} = 8$ \text{TeV}. The particles and the jets are measured in the pseudorapidity ranges $|\eta| < 2.4$ and $1.9$, respectively.

Differential top quark pair production cross-sections in $pp$ collisions at $\sqrt{s} = 8$ TeV (CMS_2015_I1370682)

Inspire | HepData | Eur.Phys.J. C75 (2015) 542 (the analysis) | CMS-PAS-TOP-15-011 (Rivet implementation)

The reconstruction of particle-level top quarks and anti-quarks is implemented in this module. Measurements at $\sqrt{s} = 8 \text{TeV}$ are based on parton-level information in the full phase space using MADGRAPH+PYTHIA6. To match the particle-level top quark distributions to the measurements unfolded to the parton-level, a correction function to the particle-level distributions, derived using the same MADGRAPH+PYTHIA6 configuration that was used for the original measurement of the data points, is applied. Using the same MC configuration as used for the unfolding to correct back the parton-level to particle-level, the model dependence introduced in unfolding to parton-level and extrapolating the measurement to the full phase space is eliminated. See the paper for full object selection and correction details.

Measurement of diffraction dissociation cross sections in pp collisions at sqrt(s)=7 TeV (CMS_2015_I1356998)

Inspire | HepData | CMS-FSQ-12-005 | CERN-PH-EP-2015-062 | ARXIV:1503.08689 [hep-ex]

Measurements of diffractive dissociation cross sections in pp collisions at $\sqrt{s}=7$ TeV are presented in kinematic regions defined by the masses $M_{\mathrm{X}}$ and $M_{\mathrm{Y}}$ of the two final-state hadronic systems separated by the largest rapidity gap in the event. Differential cross sections are measured as a function of $\xi_{\mathrm{X}}= M^2_{\mathrm{X}}/s$ in the region $-5.5<\log_{10}\xi_{\mathrm{X}}<-2.5$, for $\log_{10}M_{\mathrm{Y}}<0.5$, dominated by single dissociation (SD), and $0.5<\log_{10}M_{\mathrm{Y}}<1.1$, dominated by double dissociation (DD), where $M_{\mathrm{X}}$ and $M_{\mathrm{Y}}$ are given in GeV. The inclusive pp cross section is also measured as a function of the width of the central pseudorapidity gap $\Delta\eta$ for $\Delta\eta>3$, $\log_{10}M_{\mathrm{X}}>1.1$, and $\log_{10}M_{\mathrm{Y}}>1.1$, a region dominated by DD. The cross sections integrated over these regions are used to extract the total SD and DD cross sections. In addition, the inclusive differential cross section, $\mathrm{d}\sigma / \mathrm{d}\Delta\eta^\mathrm{F}$, for events with a pseudorapidity gap adjacent to the edge of the detector, is measured over $\Delta\eta^\mathrm{F}$ = 8.4 units of pseudorapidity. The results are compared to those of other experiments and to theoretical predictions, and found compatible with slowly-rising diffractive cross sections as a function of center-of-mass energy.

Study of hadronic event-shape variables in multijet final states in $pp$ collisions at $\sqrt{s} = 7$ TeV (CMS_2014_I1305624)

Inspire | HepData | 10.1007/JHEP10(2014)087 | arXiv:1407.2856 | CMS-PAS-SMP-12-022 | CERN-PH-EP-2014-146

Event-shape variables, which are sensitive to perturbative and nonperturbative aspects of quantum chromodynamic (QCD) interactions, are studied in multijet events recorded in proton-proton collisions at $\sqrt{s}=7$ TeV. Events are selected with at least one jet with transverse momentum $p_T > 110$ GeV and pseudorapidity $\mid\eta\mid < 2.4$, in a data sample corresponding to integrated luminosities of up to $5 fb^{-1}$. The distributions of five event-shape variables in various leading jet $p_T$ ranges are compared to predictions from different QCD Monte Carlo event generators. Five event-shape variables are analyzed in this paper: the transverse thrust $\tau_{\perp}$, the total jet broadening $B_{tot}$, the total jet mass $\rho_{tot}$, the total transverse jet mass $\rho^T_{tot}$ and the third-jet resolution parameter $Y_{23}$. In the formulae below, $p_{T,i}$, $\eta_i$, and $\phi_i$ represent the transverse momentum, pseudorapidity, and azimuthal angle of the $i$th jet, and $\hat{n}_{T}$ is the unit vector that maximizes the sum of the projections of $\vec{p}_{T,i}$. The transverse thrust axis $\hat{n}_{T}$ and the beam form the so-called event plane. Based on the direction of $\hat{n}_{T}$, the transverse region is separated into an upper side $\cal{C}_U$, consisting of all jets with $\vec{p}_{T}\cdot\hat{n}_{T}$ $>$ 0, and a lower side $\cal{C}_L$, with $\vec{p}_{T}\cdot\hat{n}_{T}$ $<$ 0. The jet broadening and third-jet resolution variables require at least three jets, whereas the calculation of other variables requires at least two jets. The $\hat{n}_{T}$ vector is defined only up to a global sign - choosing one sign or the other has no consequence since it simply exchanges the upper and lower events regions. Transverse Thrust : The event thrust observable in the transverse plane is defined as \begin{eqnarray} \tau_{\perp} & \equiv & 1 - \max_{\hat{n}_{T}} \frac{\sum_i |\vec{p}_{T,i} \cdot \hat{n}_{T} |}{\sum_i p_{T,i}} \end{eqnarray} This variable probes the hadronization process and is sensitive to the modeling of two-jet and multijet topologies. In this paper ``multijet' refers to ``more-than-two-jet'. In the limit of a perfectly balanced two-jet event, $\tau_{\perp}$ is zero, while in isotropic multijet events it amounts to $(1-2/\pi)$. Jet Broadenings : The pseudorapidities and the azimuthal angles of the axes for the upper and lower event regions are defined by \begin{eqnarray} \eta_X & \equiv & \frac{\sum_{i\in{\cal{C}}_X} p_{T,i}\eta_i}{\sum_{i\in{\cal{C}}_X} p_{T,i}} , \\ \phi_X & \equiv & \frac{\sum_{i\in{\cal{C}}_X} p_{T,i}\phi_i}{\sum_{i\in{\cal{C}}_X} p_{T,i}} , \end{eqnarray} where $X$ refers to upper ($U$) or lower ($L$) side. From these, the jet broadening variable in each region is defined as \begin{eqnarray} B_{X} & \equiv & \frac{1}{2P_{T}} \sum_{i\in{\cal{C}}_X}p_{T,i}\sqrt{(\eta_i -\eta_X)^2 + (\phi_i - \phi_X)^2} , \end{eqnarray} where $P_{T}$ is the scalar sum of the transverse momenta of all the jets. The total jet broadening is then defined as \begin{eqnarray} B_{tot} & \equiv & B_{U} + B_{L}. \end{eqnarray} Jet Masses : The normalized squared invariant mass of the jets in the upper and lower regions of the event is defined by \begin{eqnarray} \rho_X & \equiv & \frac{M^2_X}{P^2}, \end{eqnarray} where $M_X$ is the invariant mass of the constituents of the jets in the region $X$, and $P$ is the scalar sum of the momenta of all constituents in both sides. The jet mass variable is defined as the sum of the masses in the upper and lower regions, \begin{eqnarray} \rho_{tot} & \equiv & \rho_U + \rho_L . \end{eqnarray} The corresponding jet mass in the transverse plane, $\rho^T_{tot}$, is also similarly calculated in transverse plane. Third-jet resolution parameter : The third-jet resolution parameter is defined as \begin{eqnarray} Y_{23} \equiv \frac{\mathrm{min}(p_{T,3}^2,[\mathrm{min}(p_{T,i}, p_{T,j})^2 \times (\Delta R_{ij})^2/R^2])}{P_{12}^2} , \end{eqnarray} where i, j run over all three jets, $(\Delta R_{ij})^2 = (\eta_i - \eta_j)^2 + (\phi_i - \phi_j)^2$, and $p_{T,3}$ is the transverse momentum of the third jet in the event. If there are more than three jets in the event, they are iteratively merged using the $k_T$ algorithm with a distance parameter $R = 0.6$. To compute $P_{12}$, three jets are merged into two using the procedure described above and $P_{12}$ is then defined as the scalar sum of the transverse momenta of the two remaining jets. The $Y_{23}$ variable estimates the relative strength of the $p_T$ of the third jet with respect to the other two jets. It vanishes for two-jet events, and a nonzero value of $Y_{23}$ indicates the presence of hard parton emission, which tests the parton showering model of QCD event generators. A test like this is less sensitive to the details of the underlying event (UE) and parton hadronization models than the other event-shape variables.

Ratios of jet pT spectra, which relate to the ratios of inclusive, differential jet cross sections (CMS_2014_I1298810)

Inspire | HepData | arXiv:1406.0324 | CMS-SMP-13-002 | CERN-PH-EP-2014-068 | Accepted by Phys. Rev. D

Ratios of jet transverse momentum spectra. The jets objects are defined using the anti-$k_{\text{T}}$ algorithm with radii of R = 0.5 and R = 0.7. The ratios are given for six 0.5 wide rapidity regions ranging from 0.0 to 3.0 and relate the ratio of inclusive, differential jet cross sections.

Studies of 4-jet production in proton-proton collisions at $\sqrt{s} = 7$ TeV (CMS_2013_I1273574)

Inspire | HepData | CMS-FSQ-12-013 | CERN-PH-EP-2013-229 | arXiv:1312.6440 | Submitted to Phys. Rev. D

Measurements are presented of exclusive 4-jet production cross sections as a function of the transverse momentum $p_T$, pseudorapidity $\eta$, as well as of correlations in azimuthal angle and $p_T$ balance among the jets. The data sample was collected at a centre-of-mass energy of 7 TeV with the CMS detector at the LHC, corresponding to an integrated luminosity of 36 pb$^{-1}$. The jets are reconstructed with the anti-$k_T$ jet algorithm in a range of $|\eta|<4.7$.

Probing color coherence effects in $pp$ collisions at $\sqrt{s} = 7$ TeV (CMS_2013_I1265659)

Inspire | HepData | CMS-SMP-12-010 | CERN-PH-EP-2013-200 | arXiv:1311.5815

A study of color coherence effects in $pp$ collisions at a center-of-mass energy of 7 TeV is presented. The data used in the analysis were collected in 2010 with the CMS detector at the LHC and correspond to an integrated luminosity of 36/pb. Events are selected that contain at least three jets and where the two jets with the largest transverse momentum exhibit a back-to-back topology. The measured angular correlation between the second- and third-leading jet is shown to be sensitive to color coherence effects, and is compared to the predictions of Monte Carlo models with various implementations of color coherence. None of the models describe the data satisfactorily.

Jet and underlying event properties as a function of particle multiplicity (CMS_2013_I1261026)

Inspire | HepData | Eur.Phys.J. C73 (2013) 2674 | arXiv:1310.4554 | CMS-FSQ-12-022, | CERN-PH-EP-2013-195

Characteristics of multi-particle production in proton-proton collisions at $\sqrt{s} = 7$ TeV are studied as a function of the charged-particle multiplicity ($N_\text{ch}$). The produced particles are separated into two classes: those belonging to jets and those belonging to the underlying event. Charged particles are measured with pseudorapidity $|\eta| < 2.4$ and transverse momentum $p_\text{T} > 0.25$ GeV. Jets are reconstructed from charged-particles only and required to have $p_\text{T} > 5$ GeV. The distributions of jet $p_\text{T}$, average $p_\text{T}$ of charged particles belonging to the underlying event or to jets, jet rates, and jet shapes are presented as functions of $N_\text{ch}$.

CMS jet mass measurement in dijet events (CMS_2013_I1224539_DIJET)

Inspire | HepData | arXiv:1303.4811

Measurements of the mass spectra of the jets in dijet and $W/Z$+jet events from proton--proton collisions at a centre-of-mass energy of 7 TeV using a data sample of integrated luminosity of 5 fb$^-1$. The jets are reconstructed using the both the anti-$k_T$ algorithm with $R=0.7$ (AK7) and the Cambridge-Aachen algorithm with $R=0.8$ (CA8) and $R=1.2$ (CA12) with several grooming techniques applied (ungroomed, filtered, pruned and trimmed). See the text of the paper for more details. For the dijet events the distributions are presented as a function of the mean mass of the two leading jets in bins of the mean p_\perp of the two jets.

Study of the underlying event at forward rapidity in proton--proton collisions at the LHC (CMS_2013_I1218372)

Inspire | HepData | JHEP 1304 (2013) 072 | 10.1007/JHEP04(2013)072 | CMS-FWD-11-003 | arXiv:1302.2394

Ratio of the energy deposited in the pseudorapidity range $-6.6 < \eta < -5.2$ for events with a charged particle jet with $|\eta|<2$ with respect to the energy in inclusive events, as a function of charged particle jet transverse momentum for $\sqrt{s}=$0.9, 2.76 and 7 TeV.

Jet-pT and dijet mass at sqrt(s) = 7 TeV (CMS_2013_I1208923)

Inspire | HepData

The single jet differential cross section has been measured as a function of the jet momentum and the dijet differential cross section as a function of the dijet mass. The data has been recorded by the CMS detector at the center of mass energy of 7 TeV. To reconstruct the jets, the anti-$k_T$ algorithm with a cone radius of $R = 0.7$ (AK7) has been used. The results are split into five rapditiy bins, ranging from 0.0 to 2.5 with a width of 0.5 each.

Measurement of the inelastic proton-proton cross section at $\sqrt{s} = 7$ TeV (CMS_2012_I1193338)

Inspire | HepData | arXiv:1210.6718 [hep-ex]

The inelastic cross-section is measured through two independent methods based on information from (i) forward calorimetry (for pseudorapidity $3 < |\eta| < 5$), in collisions where at least one proton loses more than $\xi > 5 \cdot 10^{-6}$ of its longitudinal momentum, and (ii) the central tracker ($|\eta| < 2.4$), in collisions containing an interaction vertex with more than 1, 2, or 3 tracks with $p_\perp > 200\;\text{MeV}/c$.

Measurement of the differential cross section for inclusive dijet production as a function of $\xi$ in 7 TeV proton-proton collisions. (CMS_2012_I1184941)

Inspire | HepData | arXiv:1209.1805 [hep-ex] | Submitted to Phys. Rev. D

Measurement of the differential cross section for inclusive dijet production as a function of $\xi$ which approximates the fractional momentum loss of the scattered proton in single-diffraction events. The data used has a total integrated luminosity of 2.7 nb$^{-1}$ collected during 2010 with low instantaneous luminosity. Events are selected with at least two jets in $|\eta| < 4.4$ with $p_\perp > 20$ GeV and all final states particles are used for the reconstruction of $\xi$.

Shape, Transverse Size, and Charged Hadron Multiplicity of Jets in pp Collisions at $\sqrt{s}=7$ TeV (CMS_2012_I1111014)

Inspire | HepData | hep-ex arXiv:1204.3170 | inspirehep 1111014 | http://cms-results.web.cern.ch/cms-results/public-results/publications/QCD-10-029/

Measurements of jet characteristics from inclusive jet production in proton-proton collisions at a centre-of-mass energy of 7 TeV are presented. The data sample was collected with the CMS detector at the LHC during 2010 and corresponds to an integrated luminosity of 36 inverse picobarns. The mean charged hadron multiplicity, the differential and integral jet shape distributions, and two independent moments of the shape distributions are measured as functions of the jet transverse momentum for jets reconstructed with the anti-kT algorithm. The measured observables are corrected to the particle level and compared with predictions from various QCD Monte Carlo generators.

Measurement of inclusive and exclusive dijet production ratio at large rapidity intervals at center-of-mass energy 7 TeV. (CMS_2012_I1102908)

Inspire | HepData | CMS-FWD-10-014 | CERN-PH-EP-2012-088 | arXiv:1204.0696 [hep-ex] | Submitted to the EPJ C

This is a measurement of the ratio of inclusive to exclusive dijet production as a function of the absolute distance in rapidity, $\Delta y$, between jets. The ratio of the Mueller-Navelet to exclusive dijet production is also measured. These measurements were performed with the CMS detector in proton-proton collisions at $\sqrt{s} = 7$ TeV for jets with $p_T > 35$ GeV and $|y| < 4.7$ taken from a mixture of two data samples, one of which containing dijets with moderate rapidity separation and the other containing dijets with large rapidity separation, with integrated luminosity of 33/nb and 5/pb respectively. The measured observables are corrected for detector effects.

Dijet angular distributions in $pp$ collisions at $\sqrt{s} = 7$ TeV (CMS_2012_I1090423)

Inspire | HepData | JHEP 05 (2012) 055 | doi:10.1007/JHEP05(2012)055 | arXiv:hep-ex/1202.5535

Measurement of dijet angular distributions in proton-proton collisions at a center-of-mass energy of 7 TeV. The data sample has a total integrated luminosity of 2.2 inverse femtobarns, recorded by the CMS experiment at the LHC. Normalized dijet angular distributions have been measured for dijet invariant masses from 0.4 TeV to above 3 TeV.

Measurement of forward and forward+central jets at $\sqrt{s} = 7$ TeV (CMS_2012_I1087342)

Inspire | HepData | JHEP 1206 (2012) 036 | CMS-FWD-11-002 | CERN-PH-EP-2011-179 | doi 10.1007/JHEP06(2012)036 | arXiv:1202.0704 [hep-ex]

Inclusive forward jets and forward+central jets measured by CMS at $\sqrt{s} = 7$ TeV.

Strange particle production in underlying events in proton--proton collisions at $\sqrt{s} = 7$ TeV (CMS_2012_PAS_QCD_11_010)

CMS-PAS-QCD-11-010 | http://cdsweb.cern.ch/record/1463352

Measurements of the production of $K^0_S$, $\Lambda$ and $\bar{\Lambda}$ particles in the underlying activity of events with a $p_\perp$ scale ranging from 1 to 50 GeV/$c$ in $pp$ collisions at $\sqrt{s} = 7$\;TeV.

Studies of the underlying event at 7 TeV with leading charged particles (CMS_2012_PAS_FSQ_12_020)

CERN-PH-EP-2015-291

We study charged particle production in proton--proton collisions at 7 TeV. We use the direction of the charged particle with the largest transverse momentum in each event to define three regions of $\eta$--$\phi$ space: toward, away, and transverse. The average number and the average scalar pT sum of charged particles in the transverse region are sensitive to the modeling of the underlying event. The transverse region is divided into a MAX and MIN transverse region, which helps separate the hard component (initial and final-state radiation) from the beam--beam remnant and multiple parton interaction components of the scattering.

Forward energy flow in MB and dijet events at 0.9 and 7 TeV (CMS_2011_S9215166)

Inspire | HepData | JHEP 1111 148 | doi:10.1007/JHEP11(2011)148 | arXiv:hep-ex/1110.0211

Forward energy flow measured by CMS at $\sqrt{s} = 0.9$ and 7 TeV in MB and dijet events.

Traditional leading jet UE measurement at $\sqrt{s} = 0.9$ and 7 TeV (CMS_2011_S9120041)

Inspire | HepData | J. High Energy Phys 09 (2011) 109

A measurement of the underlying activity in scattering processes with a hard scale in the several-GeV region is performed in proton-proton collisions at Energies of 0.9 and 7\;TeV, using data collected by the CMS experiment at the LHC. The production of charged particles with pseudorapidity |eta| < 2 and transverse momentum $p_\perp > 0.5$\;GeV/$c$ is studied in the azimuthal region transverse to that of the leading set of charged particles forming a track-jet. Various comparisons are made between the two different energies and also beteen two sets of cuts on p_\perp for leading track jet p_\perp-leading $> 3$\;GeV and pT-leading $> 20$\;GeV. The activity is studied using 5 types of plots. Two profile plots for the multiplicity of charged particles and the scalar sum of p_\perp. and three distributions for the two previous quantities as well as p_\perp for all the particles in the transverse region.

Measurement of ratio of the 3-jet over 2-jet cross section in $pp$ collisions at $\sqrt{s} = 7$ TeV (CMS_2011_S9088458)

Inspire | HepData | Phys. Lett. B 702 (2011) 336

A measurement of the ratio of the inclusive 3-jet to 2-jet cross sections as a function of the total jet transverse momentum, $H_T$, in the range $0.2 < H_T < 2.5$ TeV is presented. The data have been collected at a proton--proton centre-of-mass energy of 7\;TeV with the CMS detector at the LHC, and correspond to an integrated luminosity of 36/pb. Jets are anti-$k_t$ with $R = 0.5$, $p_\perp > 50\;\text{GeV}$ and $|\eta| < 2.5$.

Measurement of the inclusive jet cross-section in $pp$ collisions at $\sqrt{s} = 7$ TeV (CMS_2011_S9086218)

Inspire | HepData | http://cdsweb.cern.ch/record/1355680

The inclusive jet cross section is measured in pp collisions with a center-of-mass energy of 7 TeV at the LHC using the CMS experiment. The data sample corresponds to an integrated luminosity of 34 inverse picobarns. The measurement is made for jet transverse momenta in the range 18-1100 GeV and for absolute values of rapidity less than 3. Jets are anti-kt with $R=0.5$, $p_\perp>18$ GeV and $|y|<3.0$.

$K_s$, $\Lambda$, and Cascade$-$ transverse momentum and rapidity spectra at 900 and 7000 GeV. (CMS_2011_S8978280)

Inspire | HepData | JHEP 05 (2011) 064 | doi:10.1007/JHEP05(2011)064 | arXiv:1102.4282 [hep-ex]

The spectra of $K_S$, $\Lambda$, and Cascade- particles were measured versus transverse-momentum ($p_\perp$) and rapidity ($y$) in proton-proton collisions at center-of-mass energies 900 and 7000 GeV. The production is normalized to all non-single-diffractive (NSD) events using corrections for trigger and selection efficiency, acceptance, and branching ratios. The results cover a rapidity range of $|y| < 2$ and a $p_\perp$ range from 0 to 10 GeV ($K_S$ and $\Lambda$) and 0 to 6 GeV (Cascade-). Antiparticles are included in all measurements so only the sums of $\Lambda$ and $\bar{\Lambda}$, and Cascade$-$ and anti-Cascade$-$ are given. The rapidity distributions are shown versus $|y|$ but normalized to a unit of $y$. Ratios of $\Lambda$/$K_S$ and Cascade$-$/$\Lambda$ production versus $p_\perp$ and $|y|$ are also given, with somewhat smaller systematic uncertainties than obtained from taking the ratio of the individual distributions.' The data were corrected according to the SD/DD/ND content of the CMS trigger, as predicted by PYTHIA6. The uncertainties connected with correct or uncorrect modelling of diffraction were included in the systematic errors.

$B/\bar{B}$ angular correlations based on secondary vertex reconstruction in $pp$ collisions (CMS_2011_S8973270)

Inspire | HepData | JHEP 1103 136 | doi:10.1007/JHEP03(2011)136 | arXiv:1102.3194

The differential $B\bar{B}$ cross-section is measured as a function of the opening angle $\Delta{R}$ and $\Delta\phi$ using data collected with the CMS detector during 2010 and corresponding to an integrated luminosity of 3.1 pb$^{-1}$. The measurement is performed for three different event energy scales, characterized by the transverse momentum of the leading jet in the event (above 56 GeV, above 84 GeV and above 120 GeV). Simulated events are normalised in the region $\Delta{R} > 2.4$ and $\Delta\phi > 3/4\pi$ respectively.

Measurement of dijet angular distributions and search for quark compositeness in $pp$ collisions at $\sqrt{s} = 7$ TeV (CMS_2011_S8968497)

Inspire | HepData | Phys.Rev.Lett.106:201804,2011 | doi:10.1103/PhysRevLett.106.201804 | arXiv:hep-ex/1102.2020

Measurement of dijet angular distributions in proton-proton collisions at a center-of-mass energy of 7 TeV. The data sample, collected with single jet triggers, has a total integrated luminosity of 36 pb$^{-1}$, with jets being reconstructed using the anti-$k_t$ clustering algorithm with $R=0.5$. The data are presented for the variable $\chi$ defined as $\chi = \exp(|y_1 - y_2|)$ where $y_1$ and $y_2$ are the rapidities of the two leading (highest $p_\perp$) jets.'

Event shapes (CMS_2011_S8957746)

Inspire | HepData | Phys.Lett.B699:48-67,2011 | arXiv:1102.0068

Central transverse Thrust and Minor have been measured in proton-proton collisions at $\sqrt{s} = 7$ TeV, with a data sample collected with the CMS detector at the LHC. The sample corresponds to an integrated luminosity of 3.2 inverse picobarns. Input for the variables are anti-$k_t$ jets with $R = 0.5$.

Dijet azimuthal decorrelations in $pp$ collisions at $\sqrt{s} = 7$ TeV (CMS_2011_S8950903)

Inspire | HepData | Phys. Rev. Lett. 106 (2011) 122003 | arXiv:1101.5029 [hep-ex]

Measurements of dijet azimuthal decorrelations in $pp$ collisions at $\sqrt{s} = 7$ TeV using the CMS detector at the CERN LHC are presented. The analysis is based on an inclusive dijet event sample corresponding to an integrated luminosity of 2.9/pb. Jets are anti-$k_t$ with $R = 0.5$, $p_\perp > 80 (30)$ GeV and $|\eta| < 1.1$.

Production cross-sections of muons from $b$ hadron decays in $pp$ collisions (CMS_2011_S8941262)

Inspire | HepData | JHEP 1103,090 | doi:10.1007/JHEP03(2011)090 | arXiv:hep-ex/1101.3512

A measurement of the $b$-hadron production cross-section in proton-proton collisions at $\sqrt{s} = 7$ TeV. The dataset, corresponding to 85 inverse nanobarns, was recorded with the CMS experiment at the LHC using a low-threshold single-muon trigger. Events are selected by the presence of a muon with transverse momentum greater than 6 GeV with respect to the beam direction and pseudorapidity less than 2.1. The transverse momentum of the muon with respect to the closest jet discriminates events containing $b$ hadrons from background. The inclusive $b$-hadron production cross section is presented as a function of muon transverse momentum and pseudorapidity.

Measurement of the NSD charged particle multiplicity at $\sqrt{s} = 0.9$, 2.36, and 7 TeV with the CMS detector. (CMS_2011_S8884919)

Inspire | HepData | J. High Energy Phys. 01 (2011) 079 | doi:10.1007/JHEP01(2011)079 | arXiv:1011.5531 [hep-ex]

Measurements of primary charged hadron multiplicity distributions are presented for non-single-diffractive events in proton-proton collisions at centre-of-mass energies of $\sqrt{s} = 0.9$, 2.36, and 7 TeV, in five pseudorapidity ranges from $|\eta| < 0.5$ to $|\eta| < 2.4$. The data were collected with the minimum-bias trigger of the CMS experiment during the LHC commissioning runs in 2009 and the 7 TeV run in 2010. The average transverse momentum as a function of the multiplicity is also presented. The measurement of higher-order moments of the multiplicity distribution confirms the violation of Koba-Nielsen-Olesen scaling that has been observed at lower energies.

Pseudorapidity distributions of charged particles at $\sqrt{s} = 0.9$ and 7 TeV (CMS_2010_PAS_QCD_10_024)

CMS-PAS-QCD-10-024 | https://cdsweb.cern.ch/record/1341853?ln=en

Pseudorapidity distributions of charged particles in $pp$ collisions at $\sqrt{s} = 0.9$ and 7\;TeV with at least one central charged particle.

Charged particle transverse momentum and pseudorapidity spectra from proton-proton collisions at 7000 GeV. (CMS_2010_S8656010)

Inspire | HepData | Phys.Rev.Lett.105:022002,2010 | doi:10.1103/PhysRevLett.105.022002 | arXiv:1005.3299 [hep-ex]

Charged particle spectra are measured in proton-proton collisions at center-of-mass energies 7000 GeV. The spectra are normalized to all non-single-diffractive (NSD) events using corrections for trigger and selection efficiency, acceptance, and branching ratios. There are transverse-momentum ($p_\perp$) spectra from 0.1 to 2 GeV in bins of pseudorapidity ($\eta$) and the $p_\perp$ spectrum from 0.1 to 6 GeV for $|\eta| < 2.4$. The $\eta$ spectra come from the average of three methods and cover $|\eta| < 2.5$ and are corrected to include all $p_\perp$. The data were corrected according to the SD/DD/ND content of the CMS trigger, as predicted by PYTHIA6. The uncertainties connected with correct or incorrect modelling of diffraction were included in the systematic errors.

Charged particle transverse momentum and pseudorapidity spectra from proton-proton collisions at 900 and 2360 GeV. (CMS_2010_S8547297)

Inspire | HepData | JHEP 02 (2010) 041 | doi:10.1007/JHEP02(2010)041 | arXiv:1002.0621 [hep-ex]

Charged particle spectra are measured in proton-proton collisions at center-of-mass energies 900 and 2360 GeV. The spectra are normalized to all non-single-diffractive (NSD) events using corrections for trigger and selection efficiency, acceptance, and branching ratios. There are transverse-momentum (pT) spectra from 0.1 to 2 GeV in bins of pseudorapidity (eta) and pT spectra from 0.1 to 4 GeV for |eta|<2.4. The eta spectra come from the average of three methods and cover |eta|<2.5 and are corrected to include all pT. The data were corrected according to the SD/DD/ND content of the CMS trigger, as predicted by PYTHIA6. The uncertainties connected with correct or incorrect modelling of diffraction were included in the systematic errors.

Charged particle pseudorapidity distribution at $\sqrt{s}$=8 TeV (CMSTOTEM_2014_I1294140)

Inspire | HepData | CERN-PH-EP-2014-063 | arXiv:1405.0722 | Submitted to EPJ C

The pseudorapidity distribution of charged particles produced in proton-proton collisions at a centre-of-mass energy of 8 TeV are measured in the ranges $|\eta| < 2.2$ and $5.3 < |\eta| < 6.4$, with the CMS and TOTEM detectors, respectively. The measurement is performed with a one-side TOTEM trigger, which is sensitive to 99\% of non-diffractive interactions and diffractive interactions with masses above 3.6 GeV, for three different event selections. An inclusive sample with the least selection bias, a sample enhanced in non-single diffractive events, and a sample enhanced in single-diffractive events were selected.

Measurement of inelastic interaction cross-section in pp collisions at 7 TeV for LHCb fiducial phase-space. (LHCB_2015_I1333223)

Inspire | HepData | JHEP02:129,2015 | doi:10.1007/JHEP02(2015)129 | arXiv:1412.2500 [hep-ex]

LhCb measurement of the cross-section for inelastic proton-proton collisions at $\sqrt{s} = 7$ TeV with at least one prompt stable charged particle of transverse momentum $p_T > 0.2$ GeV/$c$ and pseudorapidity ($\eta$) in the range $2.0 < \eta < 4.5$. A prompt stable charged particle is defined as having the true impact parameter relative to the true primary vertex smaller than 200 $\mu$m.

Charged particle multiplicities and densities in $pp$ collisions at $\sqrt{s} = 7$ TeV (LHCB_2014_I1281685)

Inspire | HepData | Eur.Phys.J.C74:2888,2014 | doi:10.1140/epjc/s10052-014-2888-1 | arXiv:1402.4430 [hep-ex]

Measurement of prompt charged particle production in proton-proton collsions at a centre-of-mass energy of 7 TeV at the LHC. The measurement is performed in the kinematic range $p > 2$ GeV/$c$, $p_\perp > 0.2$ GeV/$c$ and $2.0 < \eta < 4.8$. At least one prompt charged particle per event is required. A prompt particle is defined as a particle, that either originates directly from the primary vertex or from a decay chain in which the sum of mean lifetimes does not exceed 10 ps. Charged particle multiplicities are measured in the full kinematic range as well as in regions of pseudorapidity and transverse momentum. In addition, also mean particle densities are presented as functions of pseudorapidity and transverse momentum.

Charm hadron differential cross-sections in p_\perp and rapidity (LHCB_2013_I1218996)

Inspire | HepData | Nucl.Phys. B871 (2013) 1-20 | doi:10.1016/j.nuclphysb.2013.02.010 | arXiv:1302.2864 [hep-ex] | LHCB-PAPER-2012-041, CERN-PH-EP-2013-009

Measurements of differential production cross-sections with respect to transverse momentum, $d \sigma(H_c + \mathrm{c.c.}) / d p_T$, for charm hadron species $H_c \in \{ D^0, D^+, D^\ast(2010)^+, D_s^+, \Lambda_c^+ \}$ in proton--proton collisions at center-of-mass energy $\sqrt{s}= 7$ TeV. The differential cross-sections are measured in bins of hadron transverse momentum ($p_T$) and rapidity ($y$) with respect to the beam axis in the region $0 < p_T < 8$ GeV/$c$ and $2.0 < y < 4.5$, where $p_T$ and $y$ are measured in the proton--proton CM frame. In this analysis code, it is assumed that the event coordinate system is in the proton--proton CM frame with the $z$-axis corresponding to the proton--proton collision axis (as usual). Contributions of charm hadrons from the decays of $b$-hadrons and other particles with comparably large mean lifetimes have been removed in the measurement. In this analysis code, this is implemented by counting only charm hadrons that do not have an ancestor that contains a $b$ quark.

LHCb measurement of energy flow from $pp$ collisions at $\sqrt{s} = 7$ TeV (LHCB_2013_I1208105)

Inspire | HepData | arXiv:1212.4755 [hep-ex] | Eur. Phys. J. C 73 (2012) 2421

The energy flow created in $pp$ collisions at 7 TeV within the fiducial pseudorapidity range of the LHCb detector ($1.9 < \eta < 4.9$) is measured for inclusive minimum bias interactions, hard scattering processes and events with enhanced or suppressed diffractive contribution. Plots for these four event classes are shown separately for all and charged only final state particles, respectively. The total energy flow is measured by combining the charged energy flow and a data-constrained MC estimate of the neutral component. For the two highest eta bins the data-constrained measurements of the neutral energy were extrapolated from the more central region as the LHCb electromagnetic calorimeter has no detection coverage in that phase space domain.

Measurement of prompt hadron production ratios in $pp$ collisions at $\sqrt{s} = 0.9$ and 7 TeV (LHCB_2012_I1119400)

Inspire | HepData | arXiv:1206.5160 [hep-ex]

WARNING --- particle map is incomplete for determination of promptness, assume unknown particles to have a life time of 0 --- Measurement of the production ratios of prompt charged particles (protons, pions and kaons). Promptness is defined as originating from the primary interaction, either directly, or through the subsequent decay of a resonance.

Inclusive differential $\Phi$ production cross-section as a function of $p_\text{T}$ and $y$ (LHCB_2011_I919315)

Inspire | HepData | Phys.Lett.B703:267-273,2011 | arXiv:1107.3935 [hep-ex]

Measurement of the inclusive differential $\Phi$ cross-section in $pp$ collisions at $\sqrt {s}=7$TeV in the rapidity range of $ 2.44 < y < 4.06$ and the $p_\text{T}$ range of 0.6 GeV/c $< p_\text{T} <$ 5.0 GeV/c.

$V^0$ production ratios in $pp$ collisions at $\sqrt{s}= 0.9$ and 7 TeV at LHCb (LHCB_2011_I917009)

Inspire | HepData | JHEP08:034,2011 | arXiv:1107.0882[hep-ex] | doi:10.1007/JHEP08(2011)034

This paper presents the production ratios for $\bar{\Lambda}/\Lambda$ and $\bar{\Lambda}/K_{s}^{0}$ measured by LHCb detector in 2010 at $\sqrt{s} = 0.9$ TeV and 7 TeV as functions of the transverse momentum $p_\perp$ and the rapidity $y$ in the ranges $0.15 < p_\perp < 2.50\;\text{GeV}/c$ and $2.0 < y < 4.5$, respectively. The results for the two energies are merged and represented as a function of rapidity loss $\Delta y = y_{\mathrm{beam}} - y$.

Measurement of $\sigma(pp \to b \bar{b} X$ at $\sqrt{s} = 7$ TeV in the forward region (LHCB_2010_I867355)

Inspire | HepData | arXiv:1009.2731 [hep-ex]

The average cross-section to produce $b$-flavoured or $\bar{b}$-flavoured hadrons is measured in different pseudorapidity intervals over the entire range of p_\perp, assuming the LEP (and Tevatron) fractions for fragmentation into $b$-flavoured hadrons.

LHCb differential cross section measurement of prompt $K^0_S$ production in three rapidity windows at $\sqrt{s} = 0.9$ TeV (LHCB_2010_S8758301)

Inspire | HepData | Phys.Lett.B693:69-80,2010 | arXiv:1008.3105[hep-ex]

The paper presents the cross-section and double differential cross-section measurement for prompt $K^0_S$ production in pp collisions at $\sqrt{s} = 0.9\;TeV$. The data were taken during the LHCb run in December 2009 and cover a transversal momentum range from 0 to 1.6 GeV/c. The differential production cross-section is calculated for three rapidity windows $2.5 < y < 3.0$, $3.0 < y < 3.5$ and $3.5 < y < 4.0$ as well as the whole rapidity domain $2.5 < y < 4.0$.

Measurements of longitudinal and transverse momentum distributions for neutral pions in the forward-rapidity region with the LHCf detector (LHCF_2016_I1385877)

Inspire | HepData | Phys. Rev. D 94 (2016) 032007

The differential cross sections for inclusive neutral pions as a function of transverse and longitudinal momentum in the very forward-rapidity region have been measured at the LHC with the LHC forward detector in proton-proton collisions at $s=2.76$ and $7\,$TeV and in proton-lead collisions at nucleon-nucleon center-of-mass energies of $s_{\rm NN}=5.02\,$TeV. Such differential cross sections in proton-proton collisions are compatible with the hypotheses of limiting fragmentation and Feynman scaling. Comparing proton-proton with proton-lead collisions, we find a sizable suppression of the production of neutral pions in the differential cross sections after subtraction of ultraperipheral proton-lead collisions. This suppression corresponds to the nuclear modification factor value of about $0.1-0.3$. The experimental measurements presented in this paper provide a benchmark for the hadronic interaction Monte Carlo simulation codes that are used for the simulation of cosmic ray air showers.

Measurement of very forward neutron energy spectra for 7 TeV proton-proton collisions at the Large Hadron Collider (LHCF_2015_I1351909)

Inspire | HepData | Phys. Lett. B 750 (2015) 360-366

The Large Hadron Collider forward (LHCf) experiment is designed to use the LHC to verify the hadronic-interaction models used in cosmic-ray physics. Forward baryon production is one of the crucial points to understand the development of cosmic-ray showers. We report the neutron-energy spectra for LHC $\sqrt{s}$ = 7 TeV proton--proton collisions with the pseudo-rapidity $\eta$ ranging from 8.81 to 8.99, from 8.99 to 9.22, and from 10.76 to infinity. The measured energy spectra obtained from the two independent calorimeters of Arm1 and Arm2 show the same characteristic feature before unfolding the difference in the detector responses. We unfolded the measured spectra by using the multidimensional unfolding method based on Bayesian theory, and the unfolded spectra were compared with current hadronic-interaction models. The QGSJET II-03 model predicts a high neutron production rate at the highest pseudo-rapidity range similar to our results and the DPMJET 3.04 model describes our results well at the lower pseudo-rapidity ranges. However no model perfectly explains the experimental results in the whole pseudo-rapidity range. The experimental data indicate the most abundant neutron production rate relative to the photon production, which does not agree with predictions of the models.

Measurement of forward neutral pion transverse momentum spectra for $\sqrt{s}$ = 7 TeV proton-proton collisions at LHC (LHCF_2012_I1115479)

Inspire | HepData | Phys.Rev. D86 (2012) 092001 | arXiv:1205.4578 [hep-ex]

The inclusive production rate of neutral pions has been measured by LHCf experiment during $\sqrt{s}=7$ TeV pp collision operation in early 2010. In order to ensure good event reconstruction efficiency, the range of the $\pi^0$ rapidity and $p_\perp$ are limited to $8.9 < y < 11.0$ and $p_\perp < 0.6$ GeV, respectively.

Forward charged particle pseudorapidity density in $pp$ collisions at $\sqrt{s} = 8 \text{TeV}$ using a displaced interaction point (TOTEM_2014_I1328627)

Inspire | HepData | EPJ C75,126 | CERN-PH-EP-2014-260 | arxiv:1411.4963

The pseudorapidity density of charged particles $\mathrm{d}N_\mathrm{ch}/\mathrm{d}\eta$ is measured by the TOTEM experiment in $pp$ collisions at $\sqrt{s} = 8$ TeV within the ranges $3.9 < \eta < 4.7$ and $-6.95 < \eta < -6.9$. Data were collected in a low intensity LHC run with collisions occurring at a distance of 11.25\,m from the nominal interaction point. The data sample is expected to include 96--97\% of the inelastic proton--proton interactions. The measurement reported here considers charged particles with $p_T > 0$ MeV/$c$, produced in inelastic interactions with at least one charged particle in $-7 < \eta < -6$ or $3.7 < \eta < 4.8$. The $\mathrm{d}N_\mathrm{ch}/\mathrm{d}\eta$ has been found to decrease with $|\eta|$, from $5.11 \pm 0.73$ at $\eta = 3.95$ to $1.81 \pm 0.56$ at $\eta = -6.925$.

Measurement of proton-proton elastic scattering and total cross section at $\sqrt{s} = 7\;\text{TeV}$ (TOTEM_2012_I1220862)

Inspire | HepData | CERN-PH-EP-2012-239 | http://cds.cern.ch/record/1472948

Measurement of the elastic differential cross-section in proton-proton interactions at a centre-of-mass energy $\sqrt{s} = 7\;\text{TeV}$ at the LHC. The data, which cover the $|t|$ range $0.005-0.2\;\text{GeV}^2$, were collected using Roman Pot detectors very close to the outgoing beam in October 2011, allowing the precise extrapolation down to the optical point, $t = 0$, and hence the derivation of the elastic as well as the total cross-section via the optical theorem.

Forward $\mathrm{d}N/\mathrm{d}\eta$ at 7\;TeV (TOTEM_2012_I1115294)

Inspire | HepData | Europhys.Lett. 98 (2012) 31002 | arXiv:1205.4105 | CERN-PH-EP-2012-106 | TOTEM 2012-01

The TOTEM experiment has measured the charged particle pseudorapidity density $\mathrm{d}N_\text{ch}/\mathrm{d}\eta$ in $pp$ collisions at $\sqrt{s} = 7$\,TeV for $5.3 < |\eta| < 6.4$ in events with at least one charged particle with transverse momentum above 40\;MeV/$c$ in this pseudorapidity range.

MC analysis for ttbar studies (MC_TTBAR)

This is a pure Monte Carlo study for $t\bar{t}$ production.


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