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Charged-particle multiplicity measurement in proton-proton collisions at √s = 7 TeV with ALICE at LHC

  • Author(s): Aamodt, K;
  • Abel, N;
  • Abeysekara, U;
  • Abrahantes Quintana, A;
  • Abramyan, A;
  • Adamová, D;
  • Aggarwal, MM;
  • Aglieri Rinella, G;
  • Agocs, AG;
  • Aguilar Salazar, S;
  • Ahammed, Z;
  • Ahmad, A;
  • Ahmad, N;
  • Ahn, SU;
  • Akimoto, R;
  • Akindinov, A;
  • Aleksandrov, D;
  • Alessandro, B;
  • Alfaro Molina, R;
  • Alici, A;
  • Almaráz Aviña, E;
  • Alme, J;
  • Alt, T;
  • Altini, V;
  • Altinpinar, S;
  • Andrei, C;
  • Andronic, A;
  • Anelli, G;
  • Angelov, V;
  • Anson, C;
  • Antičić, T;
  • Antinori, F;
  • Antinori, S;
  • Antipin, K;
  • Antończyk, D;
  • Antonioli, P;
  • Anzo, A;
  • Aphecetche, L;
  • Appelshäuser, H;
  • Arcelli, S;
  • Arceo, R;
  • Arend, A;
  • Armesto, N;
  • Arnaldi, R;
  • Aronsson, T;
  • Arsene, IC;
  • Asryan, A;
  • Augustinus, A;
  • Averbeck, R;
  • Awes, TC;
  • Äystö, J;
  • Azmi, MD;
  • Bablok, S;
  • Bach, M;
  • Badalà, A;
  • Baek, YW;
  • Bagnasco, S;
  • Bailhache, R;
  • Bala, R;
  • Baldisseri, A;
  • Baldit, A;
  • Bán, J;
  • Barbera, R;
  • Barnaföldi, GG;
  • Barnby, L;
  • Barret, V;
  • Bartke, J;
  • Barile, F;
  • Basile, M;
  • Basmanov, V;
  • Bastid, N;
  • Bathen, B;
  • Batigne, G;
  • Batyunya, B;
  • Baumann, C;
  • Bearden, IG;
  • Becker, B;
  • Belikov, I;
  • Bellwied, R;
  • Belmont-Moreno, E;
  • Belogianni, A;
  • Benhabib, L;
  • Beole, S;
  • Berceanu, I;
  • Bercuci, A;
  • Berdermann, E;
  • Berdnikov, Y;
  • Betev, L;
  • Bhasin, A;
  • Bhati, AK;
  • Bianchi, L;
  • Bianchi, N;
  • Bianchin, C;
  • Bielčík, J;
  • Bielčíková, J;
  • Bilandzic, A;
  • Bimbot, L;
  • Biolcati, E;
  • Blanc, A;
  • Blanco, F
  • et al.
Abstract

The pseudorapidity density and multiplicity distribution of charged particles produced in proton-proton collisions at the LHC, at a centre-of-mass energy √s= 7 TeV, were measured in the central pseudorapidity region {pipe}η{pipe} < 1. Comparisons are made with previous measurements at √s = 0.9 TeV and 2.36 TeV. At √s = 7 TeV, for events with at least one charged particle in {pipe}η{pipe} < 1, we obtain dNch/dη = 6.01 ± 0.01(stat.)+0.20-0.12(syst.). This corresponds to an increase of 57.6% ± 0.4%(stat.)+3.6-1.8%(syst.) relative to collisions at 0.9 TeV, significantly higher than calculations from commonly used models. The multiplicity distribution at 7 TeV is described fairly well by the negative binomial distribution. © 2010 CERN for the benefit of the ALICE collaboration.

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