The charged particle production in protonproton collisions is studied with the LHCb detector at a centreofmass energy of ${\sqrt{s} =7}$TeV in different intervals of pseudorapidity $\eta$. The charged particles are reconstructed close to the interaction region in the vertex detector, which provides high reconstruction efficiency in the $\eta$ ranges $2.5<\eta<2.0$ and $2.0<\eta<4.5$. 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 $\eta$. In general, the models underestimate the charged particle production.
The multiplicity distribution in $\eta$ 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 in both figures are identical with predictions from Pythia 6, Phojet and Pythia 8 in (a) and predictions of the Pythia 6 Perugia tunes with and without diffraction in (b). 
newsys[..].eps [42 KiB] HiDef png [406 KiB] Thumbnail [270 KiB] *.C file 

newsys[..].eps [42 KiB] HiDef png [437 KiB] Thumbnail [270 KiB] *.C file 

The multiplicity distribution in the forward $\eta$ 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 in both figures are identical with predictions from Pythia 6, Phojet and Pythia 8 in (a) and predictions of the Pythia 6 Perugia tunes with and without diffraction in (b). 
newsys[..].eps [16 KiB] HiDef png [204 KiB] Thumbnail [125 KiB] *.C file 

newsys[..].eps [17 KiB] HiDef png [222 KiB] Thumbnail [137 KiB] *.C file 

The KNO distributions in different bins of $\eta$. Only the the statistical uncertainties are shown. 
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The charged particle densities as a function of $\eta$ (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 $2.0<\eta<4.5$. The data in both figures are identical with predictions from Pythia 6, Phojet and Pythia 8 in (a) and predictions of the Pythia 6 Perugia tunes with and without diffraction in (b). 
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MCrap_[..].eps [13 KiB] HiDef png [135 KiB] Thumbnail [77 KiB] *.C file 

The multiplicity distribution in $\eta$ bins (shown as points with 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 events have at least one track with a $ p_{\rm T} >1.0$ $ {\mathrm{ Ge V /}c}$ in the pseudorapidity range $2.5 < \eta < 4.5$. The data in both figures are identical with predictions from Pythia 6, Phojet and Pythia 8 in (a) and predictions of the Pythia 6 Perugia tunes in (b). 
newsys[..].eps [43 KiB] HiDef png [396 KiB] Thumbnail [259 KiB] *.C file 

newsys[..].eps [39 KiB] HiDef png [319 KiB] Thumbnail [219 KiB] *.C file 

The multiplicity distribution in the forward $\eta$ 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 $ p_{\rm T} >1.0$ $ {\mathrm{ Ge V /}c}$ in the pseudorapidity range $2.5 < \eta < 4.5$. The data in both figures are identical with predictions from Pythia 6, Phojet and Pythia 8 in (a) and predictions of the Pythia 6 Perugia tunes in (b). 
newsys[..].eps [17 KiB] HiDef png [220 KiB] Thumbnail [133 KiB] *.C file 

newsys[..].eps [15 KiB] HiDef png [178 KiB] Thumbnail [103 KiB] *.C file 

The data charged particle densities as a function of $\eta$ (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 $ p_{\rm T} >1.0$ $ {\mathrm{ Ge V /}c}$ in the pseudorapidity range $2.5 < \eta < 4.5$. The shaded bands represent the total uncertainty. 
MCrap_[..].eps [13 KiB] HiDef png [123 KiB] Thumbnail [68 KiB] *.C file 

MCrap_[..].eps [10 KiB] HiDef png [95 KiB] Thumbnail [52 KiB] *.C file 

Animated gif made out of all figures. 
PAPER2011011.gif Thumbnail 
Charged particle multiplicity distribution in the pseudorapidity range $2.5<\eta<2.0$ for minimum bias events and for hard QCD events (see text). The first quoted uncertainty is statistical and the second is systematic. 
Table_1.pdf [38 KiB] HiDef png [287 KiB] Thumbnail [153 KiB] tex code 

Charged particle multiplicity distribution in the pseudorapidity range $2.0<\eta<2.5$ for minimum bias events and for hard QCD events (see text). The first quoted uncertainty is statistical and the second is systematic. 
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Charged particle multiplicity distribution in the pseudorapidity range $2.5<\eta<3.0$ for minimum bias events and for hard QCD events (see text). The first quoted uncertainty is statistical and the second is systematic. 
Table_3.pdf [38 KiB] HiDef png [290 KiB] Thumbnail [154 KiB] tex code 

Charged particle multiplicity distribution in the pseudorapidity range $3.0<\eta<3.5$ for minimum bias events and for hard QCD events (see text). The first quoted uncertainty is statistical and the second is systematic. 
Table_4.pdf [38 KiB] HiDef png [290 KiB] Thumbnail [154 KiB] tex code 

Charged particle multiplicity distribution in the pseudorapidity range $3.5<\eta<4.0$ for minimum bias events and for hard QCD events (see text). The first quoted uncertainty is statistical and the second is systematic. 
Table_5.pdf [38 KiB] HiDef png [293 KiB] Thumbnail [154 KiB] tex code 

Charged particle multiplicity distribution in the pseudorapidity range $4.0<\eta<4.5$ for minimum bias events and for hard QCD events (see text). The first quoted uncertainty is statistical and the second is systematic. 
Table_6.pdf [38 KiB] HiDef png [284 KiB] Thumbnail [151 KiB] tex code 

Charged particle multiplicity distribution in the pseudorapidity range $2.0<\eta<4.5$ for minimum bias events and for hard QCD events (see text). The first quoted uncertainty is statistical and the second is systematic. 
Table_7.pdf [38 KiB] HiDef png [598 KiB] Thumbnail [294 KiB] tex code 
Created on 20 February 2021.