Large-Scale Calculations of the Double-Beta Decay of 76Ge, 130Te, 136Xe, and 150Nd in the Deformed Self-Consistent Skyrme Quasiparticle Random-Phase Approximation

TL;DR

This study employs a deformed Skyrme QRPA approach to calculate neutrinoless double-beta decay matrix elements for several isotopes, revealing significant differences from previous models especially for 130Te and 136Xe.

Contribution

It introduces a deformed QRPA method with a specific energy-density functional to improve decay matrix element calculations, highlighting the impact of nuclear deformation and pairing.

Findings

Matrix elements for 130Te and 136Xe are significantly smaller than previous calculations.

Results for 76Ge and 150Nd align with less complex QRPA models.

Deformation and pairing differences influence the decay matrix elements.

Abstract

We use the axially-deformed Skyrme Quasiparticle Random-Phase Approximation (QRPA) together with the SkM* energy-density functional, both as originally presented and with the time-odd part adjusted to reproduce the Gamow-Teller resonance energy in 208Pb, to calculate the matrix elements governing the neutrinoless double-beta decay of 76Ge, 130Te, 136Xe, and 150Nd. Our matrix elements in 130Te and 136Xe are significantly smaller than those of previous QRPA calculations, primarily because of the difference in pairing or deformation between the initial and final nuclei. In 76Ge and 150Nd our results are similar to those of less computationally intensive QRPA calculations. We suspect the 76Ge result, however, because we are forced to use a spherical ground-state, even though the HFB indicates a deformed minimum.