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

Understand

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)].