Strange Antibaryon to Baryon Ratios in RHIC Beam Energy Scan

In statistical thermal model, the yields of strange baryons can be described by the Boltzmann distribution approximately and the yields only depend on baryon chemical potential ($\mu_{B}$) and temperature of the system ($T$), which vary with the collision energy. From the analysis of particle yield ratios, one can obtain reliable information on chemical freeze-out parameters of the hadronic final state. STAR took data at beam energies of 7.7~GeV, 11.5~GeV and 39~GeV in AuAu collisions at RHIC in 2010. In our analysis, we measure the antibaryon to baryon ratios for the three energies, and compare our results with statistical thermal model to obtain the information of the temperature and the baryon chemical potential.