2025/03/28 by Terasaki, J., Civitarese, O.
#FOS: Physical sciences #High Energy Physics - Theory (hep-th) #Nuclear Experiment (nucl-ex) #Nuclear Theory (nucl-th)
paper · doi:10.48550/arxiv.2503.22339
We calculate the nuclear matrix element (NME), effective axial-vector current coupling gAeff, and half-life of the double-β (ββ) 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-Schrödinger perturbation theory. The NME calculations are performed for the neutrinoless ββ (0νββ) and the two-neutrino ββ (2νββ) decays of 136Xe. 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 gAeff's for the ββ 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 gAeff's including those of the 0νββ NME. This leads to the conclusion that the value of gAeff can indeed be determined by the perturbed transition operator. It is in a comparable range of the gA for the 2νββ NME. The perturbation effect on the 2νββ half-life is discussed by comparing the calculated half-lives with the different gA's and the NME components.