Particle production in Au+Au collisions at beam energy scan II energies at STAR

Abstract

We report on measurements of light charged hadron production in Au+Au collisions at √SNN = 14.6, 19.6, 27, and 54.4 GeV from the second phase of the beam energy scan (BES-II) program at RHIC. Transverse mass spectra and rapidity density distributions of π±, K±, p, and ¯p are measured as a function of collision energy, centrality, and rapidity. This work extends the previously published BES-I mid-rapidity (|y| < 0.1) measurement to a rapidity of 0.9. This new rapidity dependence highlights the effects of baryon stopping for proton yields and the different production mechanisms of π± and K±. The relative abundance of these light hadrons indicates different thermodynamic environments at different energies, centralities, and rapidities. The temperature (T) and chemical potentials (μB and μS) at chemical freeze-out are reported with their dependence on rapidity to further understand the QCD phase diagram.