Charged-particle multiplicities in pp interactions at sqrt(s) = 900 GeV measured with the ATLAS detector at the LHC

Abstract

The first measurements from proton-proton collisions recorded with the ATLAS detector at the LHC are presented. Data were collected in December 2009 using a minimum-bias trigger during collisions at a centre-of-mass energy of 900 GeV. The charged-particle multiplicity, its dependence on transverse momentum and pseudorapidity, and the relationship between mean transverse momentum and charged-particle multiplicity are measured for events with at least one charged particle in the kinematic range |eta|<2.5 and pT>500 MeV. The measurements are compared to Monte Carlo models of proton-proton collisions and to results from other experiments at the same centre-of-mass energy. The charged-particle multiplicity per event and unit of pseudorapidity at eta = 0 is measured to be 1.333 +/- 0.003 (stat.) +/- 0.040 (syst.), which is 5-15% higher than the Monte Carlo models predict.

40 pages (pages 24-40 appendix with ATLAS collaboration author list), 4 figures. The data points are in the HEP-data database at: http://hepdata.cedar.ac.uk/View/8591806

References in corpus (7)

• PYTHIA 6.4 Physics and Manual
• PYTHIA 6.2 Physics and Manual
• Parton Distributions for LO Generators
• Transverse momentum and pseudorapidity distributions of charged hadrons in pp collisions at sqrt(s) = 0.9 and 2.36 TeV
• Non-perturbative QCD Effects and the Top Mass at the Tevatron
• First proton-proton collisions at the LHC as observed with the ALICE detector: measurement of the charged particle pseudorapidity density at $\sqrt{s}$ = 900 GeV
• Measurement of Particle Production and Inclusive Differential Cross Sections in pbar{p} Collisions at sqrt{s}=1.96 TeV

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