In the framework of the Color Glass Condensate, the pseudo-rapidity distributions of charged hadrons in pp and pA collisions at the LHC are studied with the UGD function from the GBW model. With a X2 analysis of the CMS data in pp collisions at √s=0.9, 2.36, 7 TeV, the normalization factor is obtained and the theoretical results are in good agreement with the experimental data. Then, considering the influence of nucleon hard partons transverse distribution on the number of participants in pA collisions by using a Glauber Monte Carlo method, we also give the predictive results for the multiplicity distributions in pPb collisions at √s=4.4 TeV.
Experiments at the Large Hadron Collider(LHC)have measured multiplicity distributions in p+p and p+Pb collisions at a new domain of collision energy.Based on considering an energy-dependent broadening of the nucleon's density distribution,charged hadron multiplicities are studied with the phenomenological saturation model and the evolution equation dependent saturation model.By assuming the saturation scale has a small dependence on the 3-dimensional root mean square(rms)radius at different energy,the theoretical results are in good agreement with the experimental data from CMS and ALICE collaboration.The predictive results in p+p collisions at s^(1/2)=14 TeV of the LHC are also given.
