Global description of beta-minus decay in even-even nuclei with the axially-deformed Skyrme finite amplitude method

TL;DR

This paper develops a method using the finite amplitude approach with Skyrme functionals to accurately compute beta-minus decay rates in deformed nuclei, fitting parameters to experimental data and estimating uncertainties across the nuclear chart.

Contribution

It introduces a novel application of the finite amplitude method with a modified Skyrme functional for global beta-decay rate calculations in deformed nuclei, including uncertainty estimation.

Findings

Good agreement with experimental beta-decay rates.

Successfully extends calculations to neutron drip line.

Provides uncertainty estimates for decay rates.

Abstract

We use the finite amplitude method for computing charge-changing Skyrme-QRPA transition strengths in axially-deformed nuclei together with a modern Skyrme energy-density functional to fit several previously unconstrained parameters in the charge-changing time-odd part of the functional. With the modified functional we then calculate rates of beta-minus decay for all medium-mass and heavy even-even nuclei between the valley of stability and the neutron drip line. We fit the Skyrme parameters to a limited set of beta-decay rates, a set of Gamow-Teller resonance energies, and a set of spin-dipole resonance energies, in both spherical and deformed nuclei. Comparison to available experimental beta-decay rates shows agreement at roughly the same level as in other global QRPA calculations. We estimate the uncertainty in our rates all the way to the neutron drip line through a construction that extrapolates the errors of known beta-decay rates in nuclei with intermediate Q values to less stable isotopes with higher Q values.