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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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