Initialization effects of nucleon profile on the $\pi$ yields in heavy-ion collisions at medium energies

Abstract

We study a problem of $\pi$ production in heavy ion collisions in the context of the Isospin-dependent Boltzmann-Uehling-Uhlenbeck (IBUU) transport model. We generated nucleon densities using two different models, the Skyrme-Hartree-Fock (SHF) model and configuration interaction shell model (SM). Indeed, inter-nucleon correlations are explicitly taken into account in SM, while they are averaged in the SHF model. As an application of our theoretical frameworks, we calculated the ${\pi }^{-}$ and ${\pi }^{+}$ yields in collisions of nuclei with $A=30-40$ nucleons. We used different harmonic oscillator lengths $b_{HO}$ to generate the harmonic oscillator basis for SM in order to study both theoretical and experimental cases. It is found that SM framework with $b_{HO}$ = 2.5 fm and SHF can be distinguished by the yield of $\pi$ mesons, in this case the density distribution calculated by the shell model produces more $\pi$ in the collision. In comparison, SM with $b_{HO}$ = 2.0 fm is characterized from SHF by the double ${\pi }^{-}/{\pi }^{+}$ ratios with different large impact parameters, from which one can find the double ${\pi }^{-}/{\pi }^{+}$ ratios of SM change smoother and are less than those of SHF.

Comments: 7 pages, 4 figures