Journal of High Energy Physics
Measurements of primary charged hadron multiplicity distributions are presented for non-single-diffractive events in proton-proton collisions at centre-of-mass energies of √s = 0.9, 2.36, and 7 TeV, in five pseudorapidity ranges from |η| < 0.5 to |η| < 2.4. The data were collected with the minimum-bias trigger of the CMS experiment during the LHC commissioning runs in 2009 and the 7 TeV run in 2010. The multiplicity distribution at √s = 0.9 TeV is in agreement with previous measurements. At higher energies the increase of the mean multiplicity with √s is underestimated by most event generators. The average transverse momentum as a function of the multiplicity is also presented. The measurement of higher-order moments of the multiplicity distribution confirms the violation of Koba-Nielsen-Olesen scaling that has been observed at lower energies.
Khachatryan, V.; Baarmand, Marc M.; Dorney, B.; Guragain, Samir; Hohlmann, Marcus; Kalakhety, Himali; Ralich, Robert M.; Vodopiyanov, Igor; and The CMS Collaboration, "Charged Particle Multiplicities In pp Interactions At √s = 0.9, 2.36, And 7 TeV" (2011). Aerospace, Physics, and Space Science Faculty Publications. 564.