Coupled-cluster calculations of neutrinoless double-beta decay in $^{48}$Ca

TL;DR

This paper employs coupled-cluster theory with chiral effective field theory interactions to calculate the nuclear matrix element for neutrinoless double-beta decay in $^{48}$Ca, providing insights into its magnitude and accuracy.

Contribution

It introduces a coupled-cluster approach combined with chiral interactions to compute decay matrix elements, validated against no-core shell model benchmarks.

Findings

The neutrinoless double-beta decay matrix element for $^{48}$Ca is relatively small.

The study provides a calibrated nuclear matrix element for two-neutrino double-beta decay.

Benchmarking shows the approach's accuracy against other ab-initio methods.

Abstract

We use coupled-cluster theory and nuclear interactions from chiral effective field theory to compute the nuclear matrix element for the neutrinoless double-beta decay of $^{48}$Ca. Benchmarks with the no-core shell model in several light nuclei inform us about the accuracy of our approach. For $^{48}$Ca we find a relatively small matrix element. We also compute the nuclear matrix element for the two-neutrino double-beta decay of $^{48}$Ca with a quenching factor deduced from two-body currents in recent ab-initio calculation of the Ikeda sum-rule in $^{48}$Ca [Gysbers et al., Nature Physics 15, 428-431 (2019)].