Charged multiplicities in pp and AA collisions at LHC

Abstract

The mid-rapidity charged particle multiplicities in pp and AA collisions at LHC energies are described in the framework of a generalized eikonal model with shadowing corrections incorporated in AA. We show that the pp data require a Pomeron intercept close to 1.2, higher than the conventional one close to 1.1. An $s^{0.11}$ energy dependence is obtained in the LHC range and beyond. The size and centrality dependence of the AA multiplicity at $\sqrt{s} = 2.76$ TeV is reproduced and its energy dependence is predicted.