Description of weak-interaction rates within the relativistic energy density functional theory

¹ Department of Physics, Faculty of Science, University of Zagreb, Bijenička c. 32, 10000 Zagreb, Croatia
² Physics Department, Faculty of Science and Letters, Yildiz Technical University, TR-34220, Esenler/Istanbul, Turkey
³ School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China
⁴ Dipartimento di Fisica, Università degli Studi di Milano, Milano, Italy and INFN, Sezione di Milano, Via Celoria 16, 20133 Milano, Italy
⁵ Institut de Physique Nuclèaire, Universitè Paris-Sud, IN2P3-CNRS, Universitè Paris-Saclay, F-91406 Orsay Cedex, France

^* e-mail: aravlic@phy.hr

Published online: 24 February 2022

Abstract

A new theoretical framework has been established and applied in the calculation of electron capture (EC) and β-decay rates in stellar environment, characterized by high density and temperature. For the description of the nuclear properties, the finite-temperature Hartree Bardeen-Cooper-Schrie_er (FTHBCS) theory based on the relativistic derivative-coupling D3C^* interaction is employed. In order to describe the charge-exchange transitions, the finitetemperature proton-neutron quasi-particle random-phase approximation is developed (FT-PNRQRPA) which includes both temperature and pairing correlations. In the FT-HBCS calculations, only the isovector pairing is included, while in the residual interaction of the FT-PNRQRPA both the isovector and isoscalar pairing contribute. In this work, results for EC and β-decay rates are presented in the temperature interval T = 0–1.5 MeV and stellar density ρY_e = 10⁷ and 10⁹ g/cm³. Both allowed 0⁺, 1⁺ and first-forbidden transitions 0⁻, 1⁻ and 2⁻ are included in the calculations. It is shown that interplay between pairing correlations and finite-temperature effects can lead to significant changes in rates. It is also important to include de-excitations, i.e. transitions with negative Q-value, that become increasingly significant at higher temperatures especially for p f -shell nuclei.