6533b7cffe1ef96bd1259715

RESEARCH PRODUCT

Systematic approach toβand2νββdecays of massA=100–136nuclei

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In this work we perform a systematic study of pairs of single-$\ensuremath{\beta}$-decaying nuclei in the mass region $A=100--136$ to extract information on the effective value of the axial-vector coupling constant ${g}_{\mathrm{A}}$. As the many-body framework we use the quasiparticle random-phase approximation (QRPA) and its proton-neutron variant (pnQRPA) in single-particle valence bases with Woods-Saxon-calculated single-particle energies. It is found that, to a reasonable approximation, ${g}_{\mathrm{A}}$ is a linear function of the mass number $A$, with a slightly different parametrization below and above the mass $A=121$. Using the values of ${g}_{\mathrm{A}}$ extracted from the linear fit, as well as an average constant value of ${g}_{\mathrm{A}}$, we calculate the two-neutrino double-$\ensuremath{\beta}$ ($2\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}$) decay half-lives of 11 ${\ensuremath{\beta}}^{\ensuremath{-}}{\ensuremath{\beta}}^{\ensuremath{-}}$ decays and 10 mixed ${\ensuremath{\beta}}^{+}$ and electron-capture (EC) decays, ${\ensuremath{\beta}}^{+}{\ensuremath{\beta}}^{+}/{\ensuremath{\beta}}^{+}\mathrm{EC}/\mathrm{ECEC}$, to both the ground state and the lowest three excited states.