# Determination of the density region of the symmetry energy probed by the $\pi^-/\pi^+$ ratio

## TL;DR

This paper discusses how the $ ext{pi}^-/ ext{pi}^+$ ratio in specific nuclear reactions can be used to probe the symmetry energy at saturation density, based on multiple independent methods.

## Contribution

It demonstrates that the $ ext{pi}^-/ ext{pi}^+$ ratio specifically probes the symmetry energy around saturation density in heavy-ion collisions.

## Key findings

- The $ ext{pi}^-/ ext{pi}^+$ ratio probes symmetry energy at saturation density.
- Multiple independent methods agree on this density region.
- The study is based on reactions at 300 MeV/nucleon at RIBF.

## Abstract

The studies, from several independent methods, consistently show that $\pi^-/\pi^+$ ratio in the $^{132}$Sn+$^{124}$Sn reaction at 300 MeV/nucleon, which is being carried out at Radioactive Isotope Beam Facility (RIBF) in Japan, just probes the symmetry energy around saturation density.