Nucleus giant resonances from an improved isospin-dependent Boltzmann-Uehling-Uhlenbeck transport approach

TL;DR

This study improves a transport model to analyze giant resonances in lead-208, constraining nuclear symmetry energy parameters and highlighting the importance of nucleon-nucleon collisions for accurate predictions.

Contribution

The paper introduces an enhanced isospin-dependent transport approach that better reproduces giant resonance properties and constrains symmetry energy parameters.

Findings

Constrained symmetry energy slope parameter to 36-62 MeV.

Identified nucleon-nucleon collisions significantly affect electric dipole polarizability.

Provided insights into isovector nuclear interactions.

Abstract

We have studied the isoscalar giant quadruple resonance (ISGQR) and the isovector giant dipole resonance (IVGDR) in $^{208}$Pb based on an improved isospin-dependent Boltzmann-Uehling-Uhlenbeck transport approach using an improved isospin- and momentum-dependent interaction. With the isoscalar nucleon effective mass and the nucleon-nucleon cross section which reproduces respectively the excitation energy and the width of the ISGQR strength function, the slope parameter of the symmetry energy and the neutron-proton effective mass splitting are constrained respectively within $36<L<62$ MeV and $0.08\delta<(m_{n0}^*-m_{p0}^*)/m<0.42\delta$, by comparing the resulting centroid energy of the IVGDR and the electric dipole polarizability with the experimental data. It is found that nucleon-nucleon collisions have considerable effects on the resulting electric dipole polarizability, which needs to be measured more accurately in order to pin down isovector nuclear interactions.