Probing In-Medium Effect via Giant Dipole Resonance in the Extended Quantum Molecular Dynamics Model

This article uses a stochastic approach to analyze the collision term, rather than the geometric method used in the original EQMD model, to examine the width of the isovector giant dipole resonance (GDR) in ${}^{208}$Pb. Based on the ``soft" EQMD model, the response and strength functions are self-consistently determined for various symmetry energy coefficient and in-medium reduction factor values. The results confirm that the peak position and GDR width in ${}^{208}$Pb are highly sensitive to the symmetry energy and the in-medium nucleon-nucleon ({\it NN}) cross section. This provides an opportunity to study the nuclear equation of state (EoS) and the medium effect. A significant reduction in free {\it NN} elastic cross sections within the medium is necessary to accurately reproduce the GDR width, as demonstrated by a comparison with evaluation data.