Octupole correlations in low-lying states of 150Nd and 150Sm and their impact on neutrinoless double-beta decay

TL;DR

This study uses a relativistic energy-density functional to analyze low-lying states and octupole correlations in 150Nd and 150Sm, assessing their impact on neutrinoless double-beta decay matrix elements.

Contribution

It provides a detailed generator-coordinate calculation of nuclear spectra and matrix elements, highlighting the modest quenching effect of octupole correlations.

Findings

Octupole correlations reduce quadrupole collectivity.

Shape fluctuations dilute octupole effects on decay matrix elements.

Octupole-induced quenching of the matrix element is about 7%.

Abstract

We present a generator-coordinate calculation, based on a relativistic energy-density functional, of the low-lying spectra in the isotopes $^{150}$Nd and $^{150}$Sm and of the nuclear matrix element that governs the neutrinoless double-beta decay of the first isotope to the second. We carefully examine the impact of octupole correlations on both nuclear structure and the double-beta decay matrix element. Octupole correlations turn out to reduce quadrupole collectivity in both nuclei. Shape fluctuations, however, dilute the effects of octupole deformation on the double-beta decay matrix element, so that the overall octupole-induced quenching is only about 7\%.