Isospin-Dependence of ${\pi }^{-}/{\pi }^{+}$ Ratio and Density-Dependence of Nuclear Symmetry Energy

Abstract

The ${\pi }^{-}/{\pi }^{+}$ ratio is examined as a function of isospin asymmetry and beam energy for central collisions induced by neutron-rich nuclei within an isospin-dependent hadronic transport model. The ${\pi }^{-}/{\pi }^{+}$ ratio is found to increase with the isospin asymmetry, but decrease with the beam energy of the reaction. For neutron-rich systems, such as, ${}^{124}Sn{+}^{124}Sn$ and ${}^{132}Sn{+}^{124}Sn$, the sensitivity of ${\pi }^{-}/{\pi }^{+}$ ratio to nuclear symmetry energy is almost beam energy independent.

Comments: 8 pages + 2 figures. Phys. Rev. C in press