Neutrinoless double beta decay of calcium isotopes

Abstract

In this work, we compare neutrinoless double beta decay (0νββ) nuclear matrix elements (NMEs) in calcium isotopes obtained with two different methods, the nuclear shell model (NSM) and the generator coordinate method (GCM). We describe the steps needed to proceed with the calculations, and give indications on how to select reliable results. Additionally, we estimate the error in the GCM results. The 56Ca isotope shows the biggest NME discrepancy, when comparing GCM to NSM, with 34%. For 44Ca and 52Ca, there is only a 7% and 5% discrepancy, and a slightly larger one of 24% for 48Ca.