Measurement of charged particle multiplicities in pp collisions at √s = 7 TeV in the forward region

The preprint is available here.

Eur. Phys. J. C 72 (2012) 1947

arXiv:1112.4592

More detailed information:ANA note 2011-044

Abstract

The charged particle production in proton-proton collisions is studied with the LHCb detector at a centre-of-mass energy of √s=7TeV in different intervals of pseudorapidity η. The charged particles are reconstructed close to the interaction region in the vertex detector, which provides high reconstruction efficiency in the η ranges −2.5<η<−2.0 and 2.0<η<4.5. The data were taken with a minimum bias trigger, only requiring one or more reconstructed tracks in the vertex detector. By selecting an event sample with at least one track with a transverse momentum greater than 1 GeV/c a hard QCD subsample is investigated. Several event generators are compared with the data; none are able to describe fully the multiplicity distributions or the charged particle density distribution as a function of η. In general, the models underestimate the charged particle production.

Figures

(Note, eps versions are available under attachments).

Caption Figure
The multiplicity distribution in η bins (shown as points with statistical error bars) with predictions of different event generators. The inner error bar represents the statistical uncertainty and the outer error bar represents the systematic and statistical uncertainty on the measurements. The data are identical with predictions from Pythia 6, Phojet and Pythia 8. Fig1a.png
The multiplicity distribution in η bins (shown as points with statistical error bars) with predictions of different event generators. The inner error bar represents the statistical uncertainty and the outer error bar represents the systematic and statistical uncertainty on the measurements. The data are identical with predictions from Pythia 6 Perugia tunes with and without diffraction. Fig1b.png
The multiplicity distribution in the forward η range (shown as points with error bars) with predictions of different event generators. The shaded bands represent the total uncertainty on the measurements. The data are identical with predictions from Pythia 6, Phojet and Pythia 8. Fig2a.png
The multiplicity distribution in the forward η range (shown as points with error bars) with predictions of different event generators. The shaded bands represent the total uncertainty on the measurements. The data are identical with predictions from Pythia 6 Perugia tunes with and without diffraction. Fig2b.png
The KNO distributions in different bins of η. Only the the statistical uncertainties are shown. Fig3.png
The charged particle densities as a function of η (shown as points with statistical error bars) and comparisons with predictions of event generators, as indicated in the key. The shaded bands represent the total uncertainty. The events are selected by requiring at least one charged particle in the range 2.0 < η < 4.5. The data are identical with predictions from Pythia 6, Phojet and Pythia 8. Fig4a.png
The charged particle densities as a function of η (shown as points with statistical error bars) and comparisons with predictions of event generators, as indicated in the key. The shaded bands represent the total uncertainty. The events are selected by requiring at least one charged particle in the range 2.0 < η < 4.5. The data are identical with predictions from Pythia 6 Perugia tunes with and without diffraction. Fig4b.png
The multiplicity distribution in η bins (shown as points with error bars) with pre- dictions of different event generators. The inner error bar represents the statistical uncertainty and the outer error bar represents the systematic and statistical uncertainty on the measure- ments. The events have at least one track with a pT > 1.0GeV/c in the pseudorapidity range 2.5 < η < 4.5. The data are identical with predictions from Pythia 6, Phojet and Pythia 8. Fig5a.png
The multiplicity distribution in η bins (shown as points with error bars) with pre- dictions of different event generators. The inner error bar represents the statistical uncertainty and the outer error bar represents the systematic and statistical uncertainty on the measure- ments. The events have at least one track with a pT > 1.0GeV/c in the pseudorapidity range 2.5 < η < 4.5. The data are identical with predictions from Pythia 6 Perugia tunes with and without diffraction. Fig5b.png
The multiplicity distribution in the forward η range (shown as points with statistical error bars) with predictions of different event generators. The shaded bands represent the total uncertainty. The events have at least one track with a pT > 1.0GeV/c in the pseudorapidity range 2.5 < η < 4.5. The data are identical with predictions from Pythia 6, Phojet and Pythia 8. Fig6a.png
The multiplicity distribution in the forward η range (shown as points with statistical error bars) with predictions of different event generators. The shaded bands represent the total uncertainty. The events have at least one track with a pT > 1.0GeV/c in the pseudorapidity range 2.5 < η < 4.5. The data are identical with predictions from Pythia 6 Perugia tunes with and without diffraction. Fig6b.png
The data charged particle densities as a function of η (shown as points with statistical error bars) and comparisons with predictions of event generators, as indicated in the key. The events have at least one track with a pT > 1.0 GeV/c in the pseudorapidity range 2.5 < η < 4.5. The shaded bands represent the total uncertainty. Fig7a.png
The data charged particle densities as a function of η (shown as points with statistical error bars) and comparisons with predictions of Pythia 6 Perugia tunes, as indicated in the key. The events have at least one track with a pT > 1.0 GeV/c in the pseudorapidity range 2.5 < η < 4.5. The shaded bands represent the total uncertainty. Fig7b.png

-- TaraShears - 31-Mar-2012

-- TaraShears - 18-Sep-2012

Topic attachments
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PNGpng Fig1a.png r1 manage 56.4 K 2012-09-18 - 15:34 TaraShears  
Unknown file formateps Fig1b.eps r1 manage 42.8 K 2012-09-18 - 15:34 TaraShears  
PNGpng Fig1b.png r1 manage 57.7 K 2012-09-18 - 15:34 TaraShears  
Unknown file formateps Fig2a.eps r1 manage 17.0 K 2012-09-18 - 15:34 TaraShears  
PNGpng Fig2a.png r1 manage 31.1 K 2012-09-18 - 15:34 TaraShears  
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PNGpng Fig2b.png r1 manage 32.4 K 2012-09-18 - 15:34 TaraShears  
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PNGpng Fig3.png r1 manage 82.0 K 2012-09-18 - 15:34 TaraShears  
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PNGpng Fig4a.png r1 manage 21.8 K 2012-09-18 - 15:34 TaraShears  
Unknown file formateps Fig4b.eps r1 manage 13.5 K 2012-09-18 - 15:34 TaraShears  
PNGpng Fig4b.png r1 manage 23.7 K 2012-09-18 - 15:34 TaraShears  
Unknown file formateps Fig5a.eps r1 manage 43.7 K 2012-09-18 - 15:34 TaraShears  
PNGpng Fig5a.png r1 manage 56.3 K 2012-09-18 - 15:34 TaraShears  
Unknown file formateps Fig5b.eps r1 manage 39.7 K 2012-09-18 - 15:33 TaraShears  
PNGpng Fig5b.png r1 manage 44.1 K 2012-09-18 - 15:33 TaraShears  
Unknown file formateps Fig6a.eps r1 manage 17.8 K 2012-09-18 - 15:33 TaraShears  
PNGpng Fig6a.png r1 manage 32.3 K 2012-09-18 - 15:33 TaraShears  
Unknown file formateps Fig6b.eps r1 manage 15.5 K 2012-09-18 - 15:33 TaraShears  
PNGpng Fig6b.png r1 manage 25.5 K 2012-09-18 - 15:33 TaraShears  
Unknown file formateps Fig7a.eps r1 manage 13.1 K 2012-09-18 - 15:33 TaraShears  
PNGpng Fig7a.png r1 manage 21.7 K 2012-09-18 - 15:33 TaraShears  
Unknown file formateps Fig7b.eps r1 manage 10.8 K 2012-09-18 - 15:33 TaraShears  
PNGpng Fig7b.png r1 manage 17.2 K 2012-09-18 - 15:33 TaraShears  
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