Spires | 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.
Spires | 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 $|\eta|$.