Gamow-Teller excitations at finite temperature: Competition between pairing and temperature effects

TL;DR

This paper develops finite temperature proton-neutron quasiparticle random phase approximation methods to study how pairing and temperature influence Gamow-Teller excitations in open-shell nuclei, with implications for astrophysical processes.

Contribution

It introduces two FT-PNQRPA frameworks using different nuclear interactions to analyze the interplay of pairing and temperature effects on Gamow-Teller excitations.

Findings

Gamow-Teller excitations are sensitive to temperature and pairing below critical temperatures.

Both isoscalar and isovector pairing significantly affect excitation properties.

The methods enable future studies of weak processes in hot nuclear environments.

Abstract

The relativistic and nonrelativistic finite temperature proton-neutron quasiparticle random phase approximation (FT-PNQRPA) methods are developed to study the interplay of the pairing and temperature effects on the Gamow-Teller excitations in open-shell nuclei, as well as to explore the model dependence of the results by using two rather different frameworks for effective nuclear interactions. The Skyrme-type functional SkM* is employed in the nonrelativistic framework, while the density-dependent meson-exchange interaction DD-ME2 is implemented in the relativistic approach. Both the isoscalar and isovector pairing interactions are taken into account within the FT-PNQRPA. Model calculations show that below the critical temperatures the Gamow-Teller excitations display a sensitivity to both the finite temperature and pairing effects, and this demonstrates the necessity for implementing both in the theoretical framework. The established FT-PNQRPA opens perspectives for the future complete and consistent description of astrophysically relevant weak interaction processes in nuclei at finite temperature such as $\beta$-decays, electron capture, and neutrino-nucleus reactions.