Sensitivity analysis of $\beta$-decay half-life predictions for Ge, As, Zr and Mo nuclei within the mapped interacting boson model

TL;DR

This paper investigates how sensitive $eta$-decay half-life predictions are within the mapped interacting boson model (IBM) and IBFFM for certain isotopes, highlighting the impact of model parameters and higher-order terms.

Contribution

It introduces a novel application of the mapped IBM framework to compute $eta$-decay half-lives and assesses parameter sensitivities affecting decay predictions.

Findings

$eta$-decay predictions are highly sensitive to quadrupole-quadrupole interaction strength.

Higher-order transfer operators have non-negligible effects but do not change qualitative decay features.

The model reasonably reproduces observed $eta$-decay trends along isotopic chains.

Abstract

We analyze parameter sensitivities of the mapped interacting boson model (IBM) and boson-fermion-fermion model (IBFFM) in the description of $\beta$-decay properties of the even-mass neutron-deficient Ge and As, and neutron-rich Zr and Mo isotopes. Based on the self-consistent mean-field calculations with a given energy density functional and a pairing interaction, the IBM Hamiltonian for even-even nuclei, single-particle energies, and occupation probabilities for unpaired nucleons, which are necessary building blocks of the IBFFM Hamiltonian and Gamow-Teller and Fermi transition operators, are completely determined. A few coupling constants of the boson-fermion and residual neutron-proton interactions are only phenomenological parameters fitted to reproduce low-energy spectra of odd-mass and odd-odd nuclei. It is found that the calculated $\log{}_{10}ft$ values for the $\beta^+$ decays $^{68}$As$\to^{68}$Ge are particularly sensitive to the quadrupole-quadrupole boson interaction strength used for the parent ($^{68}$As) nucleus. We further incorporate higher-order terms in the one-nucleon transfer operators in the boson system, and find that, while their effects are non-negligible, they do not significantly alter qualitative features of $\beta$-decay properties. We report a novel application of the mapped IBM framework to compute $\beta$-decay half-lives, and show that the observed trend along isotopic chains are reasonably reproduced.