Extension of Glauber-like model for Proton-Proton collisions using anisotropic and inhomogeneous density profile

Abstract

Results from proton-proton (pp) collisions have routinely been used as a baseline to analyze and understand the production of QCD matter expected to be produced in nuclear collisions. But recent studies of small systems formed in pp collisions at the LHC energies hint at the possibility of producing medium with collective behavior. Therefore, results from pp collisions required more careful investigation to understand whether QCD matter is produced in high multiplicity pp collisions. With this motivation, the Glauber model traditionally used to study the heavy-ion collision dynamics at high energy is applied here to understand the dynamics of pp collisions. We have used anisotropic and inhomogeneous quark/gluon-based proton density profile, a realistic picture obtained from deep inelastic scattering results and this model explains the charged particle multiplicity distribution of pp collisions at LHC energies very well. Collision geometric properties like impact parameter and mean number of binary collisions ( N coll ), mean number of participants ( N part ) at different multiplicities are determined for pp collisions. We further used these collision geometric properties to estimate average charged-particle pseudorapidity density ( dN ch /dη ) and found it to be comparable with the experimental results. Knowing N coll , we have obtained nuclear modification-like factor (R pp ) in pp collisions which has not been done before to the best of our knowledge.