Benchmark neutrinoless double-beta decay matrix elements in a light nucleus

TL;DR

This paper benchmarks two advanced many-body nuclear physics methods, the No-Core Shell Model and the In-Medium Similarity Renormalization Group, by calculating neutrinoless double-beta decay matrix elements in a light nucleus, aiding future research in heavier systems.

Contribution

It provides a direct comparison of two state-of-the-art many-body approaches for neutrinoless double-beta decay matrix elements in a light nucleus, using consistent interactions and approximations.

Findings

Significant agreement in decay matrix elements between the two methods.

Differences observed in predicted nuclear radii and energies.

Implications discussed for calculations in heavier nuclei.

Abstract

We compute nuclear matrix elements of neutrinoless double-beta decay mediated by light Majorana-neutrino exchange in the A = 6 system. The goal is to benchmark two many-body approaches, the No-Core Shell Model and the Multi-Reference In-Medium Similarity Renormalization Group. We use the SRG-evolved chiral N3LO-EM500 potential for the nuclear interaction, and make the approximation that isospin is conserved. We compare the results of the two approaches as a function of the cutoff on the many-body basis space. Although differences are seen in the predicted nuclear radii, the ground-state energies and neutrinoless double-beta decay matrix elements produced by the two approaches show significant agreement. We discuss the implications for calculations in heavier nuclei.