LAUSR

A systematic study of the impact of widely-used nuclear-modified parton distribution function (nPDF) parameterizations on the production of direct photons and charged hadrons is per- formed by employing a next-to-leading order Monte Carlo event generator JETPHOX in hadronic collisions at LHC energies. The nuclear modification factors of photon and charged hadron produc- tions are studied in three types collision systems, small (p+p and p+Pb), medium (O+O), and large (P b + P b) in a wide rapidity acceptance. The results illustrate that the direct photon production process is a sensitive probe to decipher difference of the nPDF parameterization implementations, which provide new insights for the experimental measurements to refine the nuclear modifications on the parton distributions. To provide a benchmark for searching for quark gluon plasma in the upcoming small system measurements at LHC energies, we carry out a detailed studies of the cold nuclear matter effect in (O + O) collisions. Our outcomes show the cold nuclear matter effects are negligible for the charged hadron production in (O + O) collisions, which can be used to be as a baseline to subtract the initial state contribution.