Charged particle multiplicities in pp interactions at <span class="latex"><span class="ss">ace="symbol">脰s = 0.9span><span class="cs"><span class="math"> \sqrt {s} = 0.9 span>span>span>, 2.36, and 7 TeV
摘要
Measurements of primary charged hadron multiplicity distributions are presented for non-single-diffractive events in proton-proton collisions at centre-of-mass energies of 脰s = 0.9 \sqrt {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 脰s = 0.9 \textTeV \sqrt {s} = 0.9\;{\text{TeV}} is in agreement with previous measurements. At higher energies the increase of the mean multiplicity with 脰s \sqrt {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.