Yuan-Qing Guo | Searcharxiv

arXiv2025

Exploring the neutron-star matter properties via the deformed nuclear reactions

Within the framework of Lanzhou quantum molecular dynamics transport model, the correlation of initial deformation and isospin diffusion is systematically investigated in collisions of $^{238}$U + $^{238}$U. The impacts of the collision centrality, symmetry energy and initial configuration on the collective flows, neutron/proton and $π^{-}/π^{+}$ ratios have been systematically investigated. It is found that the broader neutron-rich region is formed in the body-body collisions in comparison with the ones in the tip-tip collisions. The neutron-star matter might be created in the density region of 0.2-0.5 $ρ_{0}$ (the normal nuclear density $ρ_{0}$=0.165 fm$^{-3}$) formed in the $^{238}$U + $^{238}$U reaction at the incident energy of 500 MeV/nucleon. The elliptic flows of protons are related to the incident energy, collision centrality, symmetry energy and collision orientation. The hard symmetry energy enables the larger free neutron/proton ratio at the beam energy of 500 MeV/nucleon. However, the neutron/proton and $π^{-}/π^{+}$ ratios in the density regime of $1.2\leq ρ/ρ_{0}\leq1.8$ are enhanced by the soft symmetry energy with the slope parameter of L=42 MeV.

nucl-th↗

arXiv2024

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

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$ρ_{0}$ - 0.8$ρ_{0}$) and high-density region (1.2$ρ_{0}$ - 1.8$ρ_{0}$) is investigated by analyzing the spectra of neutron/proton and $π^{-}/π^{+}$ 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 $π^{-}/π^{+}$ 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 $L(ρ_{0}) = 42\pm 25$ MeV by using the standard error analysis within the range of $1σ$ is obtained by analyzing the experimental data from the S$π$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.

nucl-th↗