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Transverse-momentum and pseudorapidity distributions of charged hadrons in pp collisions at sqrt(s) = 7 TeV


Charged-hadron transverse-momentum and pseudorapidity distributions in proton-proton collisions at sqrt(s) = 7 TeV are measured with the inner tracking system of the CMS detector at the LHC. The charged-hadron 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(charged)/d(eta), for |eta| < 0.5, of 5.78 +/- 0.01 (stat) +/- 0.23 (syst) for non-single-diffractive events, higher than predicted by commonly used models. The relative increase in charged-particle multiplicity from sqrt(s) = 0.9 to 7 TeV is 66.1% +/- 1.0% (stat) +/- 4.2% (syst). The mean transverse momentum is measured to be 0.545 +/- 0.005 (stat) +/- 0.015 (syst) GeV/c. The results are compared with similar measurements at lower energies.

Approved Plots from QCD-10-006

No PAS (special approval), so the approved plots are the ones in the paper.

Figure Abbreviated Caption
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Figure5.pdf Average value of dNch/deta in the central eta region as a function of centre-of-mass energy in pp and ppbar collisions. Also shown are NSD and inelastic measurements from the NAL Bubble Chamber (ppbar), ISR (pp), UA1 (ppbar), UA5 (ppbar), CDF (ppbar), STAR (pp), PHOBOS (pp), and ALICE (pp). The curves are second-order polynomial fits for the inelastic (solid) and NSD event selections (dashed). The error bars include systematic uncertainties, when available. Data points at 0.9 and 2.36 TeV are slightly displaced horizontally for visibility.

Link to the paper in CDS

Link to the paper on the Phys. Rev. Letters website

Link to the paper on ArXiv

-- GaborIVeres - 04-Aug-2010

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Topic revision: r1 - 2010-08-04 - GaborIVeres
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