Shell model analysis of the neutrinoless double-β decay of 48Ca

The neutrinoless double-beta (0 nu beta beta) decay process could provide crucial information to determine the absolute scale of neutrino masses, and it is the only one that can establish whether a neutrino is a Dirac or a Majorana particle. A key ingredient for extracting the absolute neutrino masses from 0 nu beta beta decay experiments is a precise knowledge of the nuclear matrix elements (NMEs) describing the half-life of this process. We developed a shell model approach for computing the 0 nu beta beta decay NME, and we used it to analyze the 0 nu beta beta mode of Ca-48. The dependence of the NME on the short-range correlation parameters, on the average energy of the intermediate states, on the finite-size cutoff parameters, and on the effective interaction used for many-body calculations is discussed.