Experiment of constraining symmetry energy at supra-saturation density with π^－/π⁺ at HIRFL-CSR

Abstract: 

The possibility of the experiment for constraining the symmetry energy E_sym(ρ) at supra-densities via π^－/π⁺ probe on the external target experiment of phase I ( ETE(I) ) with part coverage at forward angle at HIRFL-CSR is studied for the first time by using the isospin and momentum dependent hadronic transport model IBUU04. Based on the transport simulation with Au+Au collisions at 400 MeV/u, it is found that the differential π^－/π⁺ ratios are more sensitive to E_sym(ρ) at forward angles in laboratory reference, compared with the total yield ratio widely proposed. The insufficient coverage at lower transverse momentum maintains the sensitivity of the dependence of π^－/π⁺ ratio on the E_sym(ρ) at high density, indicating that the ETF (I) under construction in Lanzhou provides the possibility of performing the experiment for probing the asymmetric nuclear equation of state.