Measurement of charged particle multiplicities in pp collisions at $\sqrt{s} =7~\mbox{TeV}$ in the forward region

Abstract

Charged particle production in proton-proton collisions is studied with the LHCb detector at a centre-of-mass energy of √ s = 7 TeV in different intervals of pseudorapidity η. 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 charged particle production.

Forward-backward correlations and charged-particle azimuthal distributions in pp interactions using the ATLAS detector

“…Such correlations are the subject of the first part of the present study, which was carried out using proton-proton collisions recorded with the ATLAS detector [15] at the LHC. 1 The measurements were inspired by earlier work by the UA5 experiment [16] and follow published studies at the LHC of the multiplicities themselves [17][18][19][20][21]. They also complement an earlier analysis by CMS of charged-particle correlations [22] and a recent analysis by ATLAS of two-particle correlations [23].…”

Measurement of charged particle multiplicities and densities in pp collisions at 7 TeV in the forward region

“…The measurement is performed in the kinematic range p > 2 GeV/c, p T > 0.2 GeV/c and 2.0 < η < 4.8, in which at least one charged particle per event is required. By using the full spectrometer information, it is possible to extend the previous LHCb results [2] to include momentum dependent measurements.…”

“…An accurate description of the soft component of the interaction, known as the underlying event, is vital for understanding backgrounds in beyond the Standard Model searches or precision measurements of the Standard Model parameters. The forward region was previously studied with the LHCb detector, where an inclusive multiplicity measurement without momentum information was performed [2].…”

Comparative study of charged multiplicities and moments inppcollisions ats=7 TeVin the forward region at the LHC

“…The charged particle multiplicity at the LHC has been measured by CMS, ATLAS, and ALICE experiments [22][23][24] mainly in the central region. While the LHCb experiment is the only experiment to measure it in the forward region at ffiffi ffi s p ¼ 7 TeV [25], it studied the multiplicity distributions in different phase space slices, in comparison to predictions from several Monte Carlo event generators.…”