Nuclear charge-exchange excitations based on relativistic density-dependent point-coupling model

TL;DR

This paper develops a relativistic density-dependent point-coupling model to accurately describe nuclear charge-exchange excitations, improving predictions of isobaric analog and Gamow-Teller resonances relevant for astrophysical processes.

Contribution

The paper introduces a proton-neutron relativistic QRPA framework with an improved density-dependent interaction for better modeling of spin-isospin responses in nuclei.

Findings

Accurately reproduces experimental IAR energies in Sn isotopes

GTR properties depend on isoscalar pairing strength

Framework enables large-scale calculations for stellar environments

Abstract

Spin-isospin transitions in nuclei away from the valley of stability are essential for the description of astrophysically relevant weak interaction processes. While they remain mainly beyond the reach of experiment, theoretical modeling provides important insight into their properties. In order to describe the spin-isospin response,vcthe proton-neutron relativistic quasiparticle random phase approximation (PN-RQRPA) is formulated using the relativistic density-dependent point coupling interaction, and separable pairing interaction in both the $T=1$ and $T=0$ pairing channels. By implementing recently established DD-PCX interaction with improved isovector properties relevant for the description of nuclei with neutron-to-proton number asymmetry, the isobaric analog resonances (IAR) and Gamow-Teller resonances (GTR) have been investigated. In contrast to other models that usually underestimate the IAR excitation energies in Sn isotope chain, the present model accurately reproduces the experimental data, while the GTR properties depend on the isoscalar pairing interaction strength. This framework provides not only an improved description of the spin-isospin response in nuclei, but it also allows future large scale calculations of charge-exchange excitations and weak interaction processes in stellar environment.