Multiplicity distributions in the forward rapidity region in proton-proton collisions at the Large Hadron Collider

Abstract

Measured multiplicity distributions of primary charged particles produced in the forward rapidity region of the proton-proton ($pp$) collisions at the center-of-mass energy, $\sqrt{s}=7\text{ }\text{ }\mathrm{TeV}$, at the LHC have been analyzed in terms of the negative binomial distribution function. Like the multiplicity distributions in the midrapidity region for the $pp$ collisions at $\sqrt{s}=7\text{ }\text{ }\mathrm{TeV}$, the distributions for the minimum bias events in the forward region are also better described with the superposition of two negative binomail distributions, as proposed by a two-component model of particle production from two processes, the soft and the hard. However, the multiplicity distribution for the ``hard-QCD'' events in a large pseudorapidity window does not oblige the two-component model.