Yoritaka Iwata

Neutrinoless double beta decay is a pivotal weak nuclear process that holds the potential to unveil the Majorana nature of neutrinos and predict their absolute masses. In this study, we delve into examining the impact of spin-dependent short-range correlations (SRCs) on the nuclear matrix elements (NMEs) for the light neutrino-exchange mechanism in neutrinoless double beta (0νββ) decay of 48Ca, employing an extensive interacting nuclear shell model. All computations are performed employing the effective shell model Hamiltonian GXPF1A, encompassing the entire fp model space through the closure approximation. Our investigation examines the NMEs’ dependencies on factors such as the number of intermediate states, coupled spin-parity attributes of neutrons and protons, neutrino momentum, inter-nucleon separation, and closure energy. This scrutiny is performed with respect to both the conventional Jastrow-type approach of SRCs, employing various parameterizations, and the spin-dependent SRC paradigm. Our findings illuminate a discernible distinction in NMEs induced by spin-dependent SRCs, differing by approximately 10–20% from those computed through the conventional Jastrow-type SRCs, incorporating distinct parameterizations.