Shedding light on the pion production in heavy-ion collisions and application into the neutron star matter properties

• Published in: arXiv.org
• Main Authors: Heng-Jin, Liu, Zhang, Ban, Yuan-Qing, Guo, Hui-Gan, Cheng, Si-Na, Wei, Zhao-Qing, Feng
• Format: Paper
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 07.06.2024
• Subjects: Heavy ions; High density; Ionic collisions; Molecular dynamics; Pions; Stiffness; Symmetry; Transverse momentum
• ISSN: 2331-8422

Within the framework of the quantum molecular dynamics transport model, the pion production and constraint of the high-density symmetry energy in heavy-ion collisions near threshold energy have been thoroughly investigated. The energy conservation in the decay of resonances and reabsorption of pions as well as in the inelastic nucleon-nucleon and nucleon-resonance collisions are taken into account. The isospin diffusion in the low-density region (0.2\(\rho_{0}\) - 0.8\(\rho_{0}\)) and high-density region (1.2\(\rho_{0}\) - 1.8\(\rho_{0}\)) is investigated by analyzing the spectra of neutron/proton and \(\pi^{-}/\pi^{+}\) ratios in the isotopic reactions of \(^{132}\)Sn + \(^{124}\)Sn and \(^{108}\)Sn + \(^{112}\)Sn at the incident energy of 270 MeV/nucleon, in which the symmetry energy manifests the opposite effect in the different density domain. The controversial conclusion of the \(\pi^{-}/\pi^{+}\) ratio for constraining the high-density symmetry energy by different transport models with the FOPI data has been clarified. A soft symmetry energy with the slope parameter of \(L(\rho_{0}) = 42\pm 25\) MeV by using the standard error analysis within the range of \(1\sigma\) is obtained by analyzing the experimental data from the S\(\pi\)RIT collaboration. The neutron stars with the maximal mass of 2 \(M_{\odot}\) and radius of 11-13 km are obtained with the constrained symmetry energy.