Inspire | HepData | Phys.Lett. B780 (2018) 578-602 | doi:10.1016/j.physletb.2 | arXiv:1801.00112 [hep-ex]
The dynamics of isolated-photon production in association with a jet in proton-proton collisions at a centre-of-mass energy of 13 TeV are studied with the ATLAS detector at the LHC using a dataset with an integrated luminosity of 3.2 fb$^{-1}$. Photons are required to have transverse energies above 125 GeV. Jets are identified using the anti-$k_\text{t}$ algorithm with radius parameter $R=0.4$ and required to have transverse momenta above 100 GeV. Measurements of isolated-photon plus jet cross sections are presented as functions of the leading-photon transverse energy, the leading-jet transverse momentum, the azimuthal angular separation between the photon and the jet, the photon-jet invariant mass and the scattering angle in the photon-jet centre-of-mass system. Tree-level plus parton-shower predictions from Sherpa and Pythia as well as next-to-leading-order QCD predictions from Jetphox and Sherpa are compared to the measurements.
Inspire | HepData | submitted to PLB | arXiv:1710.09560 [hep-ex]
This Letter presents the measurement of differential cross sections of isolated prompt photons produced in association with a $b$-jet or a $c$-jet. These final states provide sensitivity to the heavy-flavour content of the proton and aspects related to the modelling of heavy-flavour quarks in perturbative QCD. The measurement uses proton-proton collision data at a centre-of-mass energy of 8 TeV recorded by the ATLAS detector at the LHC in 2012 corresponding to an integrated luminosity of up to 20.2 fb$^{-1}$. The differential cross sections are measured for each jet flavour with respect to the transverse energy of the leading photon in two photon pseudorapidity regions: $|\eta^\gamma| < 1.37$ and $1.56 < |\eta^\gamma| < 2.37$. The measurement covers photon transverse energies $25 < E^\gamma_\text{T} < 400$ GeV and $25 < E^\gamma_\text{T} < 350$ GeV respectively for the two $|\eta^\gamma|$ regions. For each jet flavour, the ratio of the cross sections in the two $|\eta^\gamma|$ regions is also measured. The measurement is corrected for detector effects and compared to leading-order and next-to-leading-order perturbative QCD calculations, based on various treatments and assumptions about the heavy-flavour content of the proton. Overall, the predictions agree well with the measurement, but some deviations are observed at high photon transverse energies. The total uncertainty in the measurement ranges between 13% and 66%, while the central $\gamma + b$ measurement exhibits the smallest uncertainty, ranging from 13% to 27%, which is comparable to the precision of the theoretical predictions.
Inspire | HepData | arXiv:1704.03839 [hep-ex] | submitted to PRD
A measurement of the production cross section for two isolated photons in proton--proton collisions at a center-of-mass energy of $\sqrt{s}=8$ TeV is presented. The results are based on an integrated luminosity of 20.2 fb$^{-1}$ recorded by the ATLAS detector at the Large Hadron Collider. The measurement considers photons with pseudorapidities satisfying $|\eta^\gamma| < 1.37$ or $1.56 < |\eta^\gamma| < 2.37$ and transverse energies of respectively $E^\gamma_\text{T,1}>40$ GeV and $E^\gamma_\text{T,2}> 30$ GeV for the two leading photons ordered in transverse energy produced in the interaction. The background due to hadronic jets and electrons is subtracted using data-driven techniques. The fiducial cross sections are corrected for detector effects and measured differentially as a function of six kinematic observables. The measured cross section integrated within the fiducial volume is $16.8\pm0.8$ pb. The data are compared to fixed-order QCD calculations at next-to-leading-order and next-to-next-to-leading-order accuracy as well as next-to-leading-order computations including resummation of initial-state gluon radiation at next-to-next-to-leading logarithm or matched to a parton shower, with relative uncertainties varying from 5% to 20%.
Inspire | HepData | arXiv:1605.03495 [hep-ex]
A measurement of the cross section for the inclusive production of isolated prompt photons in proton-proton collisions at a centre-of-mass energy of $\sqrt{s} = 8$ TeV is presented. The measurement covers the pseudorapidity ranges $|\eta^\gamma| < 1.37$ $1.56 < |\eta^\gamma| < 2.37$ in the transverse energy range $25 < E^\gamma_\text{T} < 1500$ GeV. The results are based on an integrated luminosity of 20.2 fb${}^{-1}$, recorded by the ATLAS detector at the LHC. Photon candidates are identified by combining information from the calorimeters and the inner tracker. The background is subtracted using a data-driven technique, based on the observed calorimeter shower-shape variables and the deposition of hadronic energy in a narrow cone around the photon candidate.
Inspire | HepData | arXiv:1311.1440 [hep-ex] | Phys.Rev. D89 (2014) 052004
A measurement of the cross section for the production of isolated prompt photons in pp collisions at a center-of-mass energy $sqrt{s} = 7$ TeV is presented. The results are based on an integrated luminosity of 4.6 fb$^{-1}$ collected with the ATLAS detector at the LHC. The cross section is measured as a function of photon pseudorapidity $\eta^\gamma$ and transverse energy $E_T^\gamma$ in the kinematic range $100 < E_T^\gamma < 1000$ GeV and in the regions $|\eta^\gamma| < 1.37$ and $1.52 < |\eta^\gamma| < 2.37$. The results are compared to leading-order parton-shower Monte Carlo models and next-to-leading order perturbative QCD calculations. Next to-leading-order perturbative QCD calculations agree well with the measured cross sections as a function of $E_T^\gamma$ and $\eta^\gamma$.
Inspire | HepData | Nucl.Phys. B875 (2013) 483-535 | doi:10.1016/j.nuclphysb.2013.07.025 | arXiv:1307.6795 [hep-ex]
Measurements of isolated photon plus jet production in $pp$ collisions at a centre-of-mass energy of 7 TeV with the ATLAS detector at the LHC using an integrated luminosity of $37 \text{pb}^{-1}$. Differential cross sections are presented as functions of photon transverse energy, jet transverse momentum and jet rapidity. In addition, the differential cross sections as functions of the difference between the azimuthal angles of the photon and the jet, the photon-jet invariant mass as well as the scattering angle in the photon-jet centre-of-mass frame have been measured.
Inspire | HepData | arXiv:1211.1913 [hep-ex] | JHEP 1301 (2013) 086
The ATLAS experiment at the LHC has measured the production cross section of events with two isolated photons in the final state, in proton-proton collisions at $\sqrt{s} = 7$ TeV. The full data set collected in 2011, corresponding to an integrated luminosity of 4.9 fb$^{-1}$, is used. The amount of background, from hadronic jets and isolated electrons, is estimated with data-driven techniques and subtracted. The total cross section, for two isolated photons with transverse energies above 25 GeV and 22 GeV respectively, in the acceptance of the electromagnetic calorimeter ($|\eta|<1.37$ and $1.52<|\eta|<2.37$) and with an angular separation $\Delta R>0.4$, is $44.0^{+3.2}_{-4.2}$ pb. The differential cross sections as a function of the di-photon invariant mass, transverse momentum, azimuthal separation, and cosine of the polar angle of the largest transverse energy photon in the Collins--Soper di-photon rest frame are also measured. The results are compared to the prediction of leading-order parton-shower and next-to-leading-order and next-to-next-to-leading-order parton-level generators.
Inspire | HepData | arXiv:1203.3161 [hep-ex]
A measurement of the production cross section for isolated photons in association with jets in $pp$ collisions at $\sqrt{s} = 7$ TeV. Photons with $|\eta|<1.37$ and $E_T>25$ GeV and jets with $|y|<4.4$ and $p_T>20$ GeV are selected. The differential cross section as a function of the photon transverse energy is measured, for three leading jet rapidity configurations, separately for the cases where the photon and jet rapidities have the same or the opposite sign. The measurement uses 37 pb$^{-1}$ of integrated luminosity collected with the ATLAS detector.
Inspire | HepData | arXiv:1108.0253 [hep-ex] | Phys.Lett. B706 (2011) 150-167
A measurement of the differential cross-section for the inclusive production of isolated prompt photons in $pp$ collisions at a center-of-mass energy $\sqrt{s} = 7$ TeV is presented. The measurement covers the pseudorapidity ranges $|\eta|<1.37$ and $1.52<|\eta|<2.37$ in the transverse energy range $45<E_T<400$ GeV. The results are based on an integrated luminosity of 35 pb$^{-1}$, collected with the ATLAS detector at the LHC. The yields of the signal photons are measured using a data-driven technique, based on the observed distribution of the hadronic energy in a narrow cone around the photon candidate and the photon selection criteria. The results are compared with next-to-leading order perturbative QCD calculations and found to be in good agreement over four orders of magnitude in cross-section.
Inspire | HepData | arXiv:1107.0581 [hep-ex]
A measurement of the cross section for inclusive isolated photon production at $\sqrt{s} = 7$ TeV. The measurement is done in bins of $M_{\gamma\gamma}$, $p_{T\gamma\gamma}$, and $\Delta\phi_{\gamma\gamma}$, for isolated photons with $|\eta|<2.37$ and $E_T^\gamma>16$ GeV. The measurement uses 37 pb$^{-1}$ of integrated luminosity collected with the ATLAS detector.
Inspire | HepData | arXiv:1012.4389 [hep-ex]
A measurement of the cross section for inclusive isolated photon production at $\sqrt{s} = 7$ TeV. The measurement covers three ranges in $|\eta|$: [0.00,0.60), [0.60,1.37), and [1.52,1.81), for $E_T^\gamma>15$ GeV. The measurement uses 880 nb$^{-1}$ of integrated luminosity collected with the ATLAS detector.
Inspire | HepData | arXiv:1311.6141 [hep-ex]
A measurement of the triple differential cross section in photon+jets final states in $pp$ collisions at $\sqrt{s} = 7$ TeV. Photons with $|\eta|<2.5$ and $40$ GeV$<p_T<300$ GeV and jets with $|\eta|<2.5$ and $p_T>30$ GeV are selected. The measurement uses 2.14 fb$^{-1}$ of integrated luminosity collected with the CMS detector.
Inspire | HepData | arXiv:1310.3082 | https://twiki.cern.ch/twiki/bin/view/CMSPublic/PhysicsResultsSMP12004 | Submitted to Phys. Rev. Lett
Rapidity distributions are presented for events containing either a $Z$ boson or a photon in association with a single jet in proton-proton collisions produced at the CERN LHC. The data, collected with the CMS detector at $\sqrt{s} = 7$ TeV, correspond to an integrated luminosity of 5.0/fb. The individual rapidity distributions of the boson and the jet are consistent within 5\% with expectations from perturbative QCD. However, QCD predictions for the sum and the difference in rapidities of the two final-state objects show significant discrepancies with CMS data. In particular, next-to-leading-order QCD calculations, and two Monte Carlo event generators using different methods to merge matrix-element partons with evolved parton showers, appear inconsistent with the data as well as with each other.
Inspire | HepData | arXiv:1111.5536 [hep-ex]
A measurement of the exclusive two-photon production of muon pairs in proton-proton collisions at at a centre-of-mass energy 7 TeV with the final state $p \mu^+ \mu^- p$, is reported using data corresponding to an integrated luminosity of 40 pb$^-1$ collected in 2010. The measured cross section is obtained with a fit to the dimuon $p_T$ distribution for muon pairs with invariant mass greater than 11.5 GeV with each muon $p_T > 4$ GeV and $|\eta| < 2.1$.
Different observables related to the two photons
Different observables related to the photon and extra jets.
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