English

Effects of perturbation for transition operator of double-${\beta}$ decay on nuclear matrix element, effective axial-vector current coupling, and half-life

Nuclear Theory 2025-08-07 v2 High Energy Physics - Theory Nuclear Experiment

Abstract

We calculate the nuclear matrix element (NME), effective axial-vector current coupling gAeffg_A^\mathrm{eff}, and half-life of the double-β\beta (ββ\beta\beta) decay using the transition operator perturbed by the nuclear interaction. The correction terms for the NME are obtained by extending the hadron sector to a higher order in terms of the Rayleigh-Schr\"{o}dinger perturbation theory. The NME calculations are performed for the neutrinoless ββ\beta\beta (0νββ0\nu\beta\beta) and the two-neutrino ββ\beta\beta (2νββ2\nu\beta\beta) decays of 136^{136}Xe. The nuclear wave functions are calculated by the quasiparticle random-phase approximation (QRPA) with the Skyrme, the Coulomb, and the contact pairing interactions. Sufficiently large single-particle valence spaces are used. The correction terms for the NME are comparable with the leading term in absolute value, and the sum of the corrections has the opposite sign to that of the leading term. The gAeffg_A^\mathrm{eff}'s for the ββ\beta\beta NME are calculated by a few methods depending on the truncation of the NME and the half-life referred to. Similarities are found between some of these gAeffg_A^\mathrm{eff}'s including those of the 0νββ0\nu\beta\beta NME. This leads to the conclusion that the value of gAeffg_A^\mathrm{eff} can indeed be determined by the perturbed transition operator. It is in a comparable range of the gAg_A for the 2νββ2\nu\beta\beta NME. The perturbation effect on the 2νββ2\nu\beta\beta half-life is discussed by comparing the calculated half-lives with the different gAg_A's and the NME components.

Keywords

Cite

@article{arxiv.2503.22339,
  title  = {Effects of perturbation for transition operator of double-${\beta}$ decay on nuclear matrix element, effective axial-vector current coupling, and half-life},
  author = {J. Terasaki and O. Civitarese},
  journal= {arXiv preprint arXiv:2503.22339},
  year   = {2025}
}

Comments

38 pages, 10 figures, revised and accepted by Physical Review C