Experiments at the Large Hadron Collider (LHC) have measured multiplicity distributions in proton-proton collisions at a new domain of center-of-mass energy ($\sqrt{s}$) in limited pseudorapidity intervals. We analyze multiplicity distribution data of proton-proton collisions at LHC energies as measured by the Compact Muon Solenoid (CMS) experiment in terms of characteristic parameters of the negative binomial distribution (NBD) function that has played a significant role in describing multiplicity distribution data of particle production in high-energy physics experiments, in the pre-LHC energy range, in various kinds of collisions for a wide range of collision energy and for different kinematic ranges. Beside a single NBD, we apply the formalism of weighted superposition of two NBDs to examine if the multiplicity distribution data of CMS could be better explained. The weighted superposition of two NBDs indeed explains the distribution data better at the highest available LHC energy and in large intervals of phase space. The two-NBD formalism further reveals that the energy invariance of the multiplicity distribution of the soft component of particle production in hadronic collisions is valid at LHC also, as it is at RHIC and Tevatron. We analyze the data further in terms of clan parameters in the framework of the two-NBD model.

• Received 23 September 2011

DOI:https://doi.org/10.1103/PhysRevD.85.054017