Transverse-Momentum and Pseudorapidity Distributions of Charged Hadrons in pp Collisions at sqrt[s]=7 TeV (original) (raw)
2010, Physical Review Letters
Charged-hadron transverse-momentum and pseudorapidity distributions in proton-proton collisions at ffiffi ffi s p ¼ 7 TeV are measured with the inner tracking system of the CMS detector at the LHC. The chargedhadron yield is obtained by counting the number of reconstructed hits, hit pairs, and fully reconstructed charged-particle tracks. The combination of the three methods gives a charged-particle multiplicity per unit of pseudorapidity dN ch =dj jj<0:5 ¼ 5:78 AE 0:01ðstatÞ AE 0:23ðsystÞ for non-single-diffractive events, higher than predicted by commonly used models. The relative increase in charged-particle multiplicity from ffiffi ffi s p ¼ 0:9 to 7 TeV is ½66:1 AE 1:0ðstatÞ AE 4:2ðsystÞ%. The mean transverse momentum is measured to be 0:545 AE 0:005ðstatÞ AE 0:015ðsystÞ GeV=c. The results are compared with similar measurements at lower energies.
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Journal of High Energy Physics, 2010
Measurements of inclusive charged-hadron transverse-momentum and pseudorapidity distributions are presented for proton-proton collisions at √ s = 0.9 and 2.36 TeV. The data were collected with the CMS detector during the LHC commissioning in December 2009. For non-single-diffractive interactions, the average charged-hadron transverse momentum is measured to be 0.46 ± 0.01 (stat.) ± 0.01 (syst.) GeV/c at 0.9 TeV and 0.50 ± 0.01 (stat.) ± 0.01 (syst.) GeV/c at 2.36 TeV, for pseudorapidities between −2.4 and +2.4. At these energies, the measured pseudorapidity densities in the central region, dN ch /dη| |η|<0.5 , are 3.48 ± 0.02 (stat.) ± 0.13 (syst.) and 4.47 ± 0.04 (stat.) ± 0.16 (syst.), respectively. The results at 0.9 TeV are in agreement with previous measurements and confirm the expectation of near equal hadron production in pp and pp collisions. The results at 2.36 TeV represent the highest-energy measurements at a particle collider to date.
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