Influence of symmetry energy on electromagnetic field during heavy-ion collisions

Abstract

Heavy-ion collision simulations in intermediate energy regime using isospin quantum molecular dynamics model have been proposed as a novel means to glean information about the high density behaviour of nuclear matter. Herein, the influence of modelling the pressure gradient by changing stiffness parameter and isospin asymmetry on the dynamics of charged particles have been investigated. In this research, three different values of stiffness parameter, \(\gamma =\) 0.66 (soft), 1 (stiff) and 2 (super-stiff), to tune the anisotropic transverse pressure gradients have been considered to explore the influence of density-dependent symmetry energy

$$\begin{aligned} & E_{\textrm{sym}}({\rho })=E_{\textrm{sym}}({\rho _{0}}) \bigg (\frac{\rho }{\rho _{0}}\bigg )^{\gamma } \end{aligned}$$

on the electromagnetic field and energy density evolution. Stiffer symmetry energy (\( \gamma =\) 2) leads to larger pressure gradient than softer symmetry energy (\( \gamma =\) 0.66) that drives stronger expansion resulting in higher intensity of \((eB_{y}(0, 0, 0))_{\textrm{max}}\) and \(\langle | \vec {E}\cdot \vec {B}|\rangle _{\textrm{max}}\). The correlation of eccentricity, nuclear stopping, centrality with the electromagnetic field and energy density have been established for different stiffness parameters. To deepen this study, the influence of isospin asymmetry (N/Z) on the time evolution of electromagnetic field has also been explored.