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

Charged particle production in proton-proton collisions is studied with the LHCb detector at a centre-of-mass energy of root s = 7 TeV in different intervals of pseudorapidity eta. 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 charged particle production. RI Galli, Domenico/A-1606-2012; Coca, Cornelia/B-6015-2012; Petrolini, Alessandro/H-3782-2011; Sarti, Alessio/I-2833-2012; Carbone, Angelo/C-8289-2012; de Paula, Leandro/I-9278-2012; manca, giulia/I-9264-2012; Patrignani, Claudia/C-5223-2009; Marconi, Umberto/J-2263-2012; de Simone, Patrizia/J-3549-2012; Cardini, Alessandro/J-5736-2012; Teodorescu, Eliza/K-3044-2012