Pseudorapidity and leading transverse momentum distributions of charged particles in pp collisions at √s = 8 TeV

Abstract

The pseudorapidity of charged particles and leading-track transverse momentum distributions in proton-proton collisions at √s = 8 TeV, are measured in the pseudorapidity range |η| < 2.4, by the CMS detector. The data correspond to an integrated luminosity of 17.4 nb-1. Events were triggered by the TOTEM T2 telescopes that cover the pseudorapidity range 5.3 < |η| < 6.5 for reconstructed tracks with pT > 40 MeV. The measurement of the pseudorapidity distributions was performed for primary charged particles with pT > 0.1 GeV and pT > 1 GeV, for two different conditions: an inclusive sample was obtained by requiring tracks reconstructed in the acceptance of the TOTEM T2 telescopes in either hemisphere, and a sample enhanced in non-single diffractive dissociation events by requiring tracks in T2 in both forward and backward hemispheres. The pT,min distribution of the leading tracks in the central region is also measured. The distribution integrated over the leading track transverse momentum above a pT,min value shows the transition from the perturbative to the non-perturbative region. For pT,min of a few GeV, a saturation of the distribution is already visible. This region is not well described by current Monte Carlo event generators.

Figures

Figure 1 Figure 1

Figure caption: Charged particle pseudorapidity distributions at √s = 8 TeV for tracks in |η| < 2.4$ with pT > 0.1 GeV. Results are shown for an inclusive sample obtained by requiring tracks in any of the T2 telescopes in either hemisphere (left) and a sample enhanced in non-single diffractive events requiring tracks in T2 in both forward and backward hemispheres (right). The data are compared to different model predictions and their ratio is shown in the lower panels. The shaded area shows the total systematic uncertainty.

Figure 2 Figure 1

Figure caption: Charged particle pseudorapidity distributions at √s = 8 TeV for tracks in |η| < 2.4$ with pT > 1 GeV. Results are shown for an inclusive sample obtained by requiring tracks in any of the T2 telescopes in either hemisphere (left) and a sample enhanced in non-single diffractive events requiring tracks in T2 in both forward and backward hemispheres (right). The data are compared to different model predictions and their ratio is shown in the lower panels. The shaded area shows the total systematic uncertainty.

Figure 2

Figure caption: Average value of dNch/d&eta in the central region as a function of the centre-of-mass energy in pp and pp̄ collisions. Shown are measurements performed with different NSD event selections from UA1, UA5, CDF, ALICE and CMS. The dashed line is a fit to the data.

Figure 3 Figure 1

Figure caption: Normalised pT-distribution of the leading track (left) and normalised integrated pT-distribution of the leading track (right) in |η| <<2.4. Data are compared to predictions obtained from different Pythia6 and Pytiha8 tunes. The statistical errors are shown as error bars and the shaded area shows the systematic uncertainty.

Figure 4 Figure 1

Figure caption: Normalised pT-distribution of the leading track (left) and normalised integrated pT-distribution of the leading track (right) in |η| <<2.4. Data are compared to predictions by different event generators. The statistical errors are shown as error bars and the shaded area shows the systematic uncertainty.

Topic attachments
I Attachment History Action Size Date Who Comment
PNGpng pt1000_inclusive.png r1 manage 48.4 K 2013-04-22 - 15:59 PanagiotisKatsas pseudorapidity distributions
PNGpng pt1000_nsd.png r1 manage 48.3 K 2013-04-22 - 15:59 PanagiotisKatsas pseudorapidity distributions
PNGpng pt100_inclusive.png r1 manage 48.3 K 2013-04-22 - 15:59 PanagiotisKatsas pseudorapidity distributions
PNGpng pt100_nsd.png r1 manage 50.6 K 2013-04-22 - 15:59 PanagiotisKatsas pseudorapidity distributions
PNGpng sqrts_vs_dndeta-data.png r1 manage 38.8 K 2013-04-22 - 16:12 PanagiotisKatsas centre-of-mass energy dependence
PNGpng track_pt_integrated_corrected_08.png r1 manage 41.2 K 2013-04-22 - 15:44 PanagiotisKatsas leading track pt distributions
PNGpng track_pt_integrated_corrected_08_mc.png r1 manage 39.8 K 2013-04-22 - 15:44 PanagiotisKatsas leading track pt distributions
PNGpng track_pt_leading_08.png r1 manage 47.3 K 2013-04-22 - 15:44 PanagiotisKatsas leading track pt distributions
PNGpng track_pt_leading_08_mc.png r1 manage 46.4 K 2013-04-22 - 15:44 PanagiotisKatsas leading track pt distributions
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Topic revision: r1 - 2013-04-22 - PanagiotisKatsas
 
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