Identified Particle Production from the BES at RHIC

Abstract

The RHIC Beam Energy Scan focuses on the study of the QCD phase diagram --- temperature ($T$) vs. baryon chemical potential ($\mu_B$). The aim is to verify some predictions from QCD: that a cross-over occurs at $\mu_B$ = 0, that there exists a first-order phase transition at large $\mu_B$ and a critical point at an intermediate $\mu_B$. The spectra and ratios of produced particles can be used to extract $T$ and $\mu_B$ in different energies and system sizes. The STAR experiment has collected data for Au+Au collisions at $\sqrt{s_{NN}}=$ 7.7 GeV, 11.5 GeV, and 39 GeV in the year 2010. We present midrapidity $p_{T}$ spectra, rapidity density, average transverse mass, and particle ratios for identified hadrons from the STAR experiment. The centrality and transverse momentum dependence of the particle yields and ratios are compared to existing data at lower and higher beam energies. The chemical and kinetic freeze-out conditions are extracted from the ratios and particle spectra.