Initial nuclear effects in the improved HIJING code and the production of charged pions, kaons and (anti)protons at STAR BES

Abstract

The improved Heavy Ion Jet Interaction Generator (HIJING) code is introduced to explore possible initial nuclear effects on the bulk observables of charged pions, kaons and (anti)protons observed in Au+Au collisions at sNN=7.7, 11.5, 19.6, 27 and 39 GeV. The standard HIJING code is extended by (i) different baryon production mechanisms, and (ii) Regge collective cascade recipe. We find that the centrality dependence of the identified particle multiplicity dN/dy at mid-rapidity is quite sensitive to Regge cascading. The overall contribution of baryon production mechanism is shown to enhance the centrality dependence of the mixed particle ratios, K±/π± and p±/π± at <Npart><200 (which corresponds to 20%−100% centrality), especially at higher collision energy. It turns out that the bulk data are shown to be more consistent with HIJING (plus a suitable hadron rescattering code) employing both an advanced popcorn baryon production mechanism and Regge initial scatterings.