Effects of pairing strength on the nuclear structure and double-$β$ decay predictions within the mapped interacting boson model

Fuente: arXiv
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Main Author: Nomura, Kosuke
Format: Preprint
Published: 2024
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author Nomura, Kosuke
author_facet Nomura, Kosuke
contents The low-energy nuclear structure and two-neutrino double-$β$ ($2νββ$) decay are studied within the interacting boson model (IBM) that is based on the nuclear energy density functional (EDF). The IBM Hamiltonian describing the initial and final even-even nuclei, and the interacting boson fermion-fermion Hamiltonian producing the intermediate states of the neighboring odd-odd nuclei are determined by the microscopic inputs provided by the self-consistent mean-field (SCMF) calculations employing a relativistic EDF and a separable pairing force. Sensitivities of the low-lying structure and $2νββ$-decay properties to the pairing strength are specifically analyzed. It is shown that the SCMF calculations with decreased and increased pairing strengths lead to quadrupole-quadrupole interaction strengths in the IBM that are, respectively, significantly enhanced and reduced in magnitude. When the increased pairing is adopted, in particular, the energy levels of the excited $0^+$ states are lowered, and the predicted $2νββ$-decay nuclear matrix elements (NMEs) increase in magnitude systematically. The mapped IBM employing the increased pairing force generates effective NMEs and half-lives that are in a reasonable agreement with the experimental data for the $^{76}$Ge$\to^{76}$Se, $^{82}$Se$\to^{82}$Kr, and $^{100}$Mo$\to^{100}$Ru decays in particular, whereas the calculation with the standard pairing strength is adequate to provide an overall good description of the effective NMEs in agreement with data.
format Preprint
id arxiv_https___arxiv_org_abs_2406_02986
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Effects of pairing strength on the nuclear structure and double-$β$ decay predictions within the mapped interacting boson model
Nomura, Kosuke
Nuclear Theory
Nuclear Experiment
The low-energy nuclear structure and two-neutrino double-$β$ ($2νββ$) decay are studied within the interacting boson model (IBM) that is based on the nuclear energy density functional (EDF). The IBM Hamiltonian describing the initial and final even-even nuclei, and the interacting boson fermion-fermion Hamiltonian producing the intermediate states of the neighboring odd-odd nuclei are determined by the microscopic inputs provided by the self-consistent mean-field (SCMF) calculations employing a relativistic EDF and a separable pairing force. Sensitivities of the low-lying structure and $2νββ$-decay properties to the pairing strength are specifically analyzed. It is shown that the SCMF calculations with decreased and increased pairing strengths lead to quadrupole-quadrupole interaction strengths in the IBM that are, respectively, significantly enhanced and reduced in magnitude. When the increased pairing is adopted, in particular, the energy levels of the excited $0^+$ states are lowered, and the predicted $2νββ$-decay nuclear matrix elements (NMEs) increase in magnitude systematically. The mapped IBM employing the increased pairing force generates effective NMEs and half-lives that are in a reasonable agreement with the experimental data for the $^{76}$Ge$\to^{76}$Se, $^{82}$Se$\to^{82}$Kr, and $^{100}$Mo$\to^{100}$Ru decays in particular, whereas the calculation with the standard pairing strength is adequate to provide an overall good description of the effective NMEs in agreement with data.
title Effects of pairing strength on the nuclear structure and double-$β$ decay predictions within the mapped interacting boson model
topic Nuclear Theory
Nuclear Experiment
url https://arxiv.org/abs/2406.02986