Charged-particle multiplicities in ppinteractions measured with the ATLAS detector at the LHC
Measurements are presented from proton-proton collisions at centre-of-mass energies of s = 0.9, 2.36 and 7 TeV recorded with the ATLAS detector at the LHC. Events were collected using a single-arm minimumbias 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. The results are compared to each other and to various Monte Carlo (MC) models, including a new AMBT1 pythia6 tune. In all the kinematic regions considered, the particle multiplicities are higher than predicted by the MC models. The central charged-particle multiplicity per event and unit of pseudorapidity, for tracks with pT < 100 MeV, is measured to be 3.483±0.009 (stat)±0.106 (syst) at s = 0.9 TeV and 5.630±0.003 (stat)±0.169 (syst) at s = 7 TeV. © 2011 CERN for the benefit of the ATLAS Collaboration, published under licence by IOP Publishing Ltd for the Institute of Physics and Deutsche Physikalische Gesellschaft.
Aad, G; Abbott, B; Abdallah, J; Abdelalim, AA; Abdesselam, A; Abdinov, O; Abi, B; Abolins, M; Abramowicz, H; Abreu, H; Acerbi, E; Acharya, BS; Ackers, M; Adams, DL; Addy, TN; Adelman, J; Aderholz, M; Adomeit, S; Adragna, P; Adye, T; Aefsky, S; Aguilar-Saavedra, JA; Aharrouche, M; Ahlen, SP; Ahles, F; Ahmad, A; Ahsan, M; Aielli, G; Akdogan, T; Åkesson, TPA; Akimoto, G; Akimov, AV; Alam, MS; Alam, MA; Albrand, S; Aleksa, M; Aleksandrov, IN; Aleppo, M; Alessandria, F; Alexa, C; Alexander, G; Alexandre, G; Alexopoulos, T; Alhroob, M; Aliev, M; Alimonti, G; Alison, J; Aliyev, M; Allport, PP; Allwood-Spiers, SE; Almond, J; Aloisio, A; Alon, R; Alonso, A; Alonso, J; Alviggi, MG; Amako, K; Amaral, P; Amelung, C; Ammosov, VV; Amorim, A; Amorós, G; Amram, N; Anastopoulos, C; Andeen, T; Anders, CF; Anderson, KJ; Andreazza, A; Andrei, V; Andrieux, ML; Anduaga, XS; Angerami, A; Anghinolfi, F; Anjos, N; Annovi, A; Antonaki, A; Antonelli, M; Antonelli, S; Antos, J; Anulli, F; Aoun, S; Aperio Bella, L; Apolle, R; Arabidze, G; Aracena, I; Arai, Y; Arce, ATH; Archambault, JP; Arfaoui, S; Arguin, JF; Arik, E; Arik, M; Armbruster, AJ; Arms, KE; Armstrong, SR; Arnaez, O; Arnault, C; Artamonov, A; Artoni, G; Arutinov, D
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