Analysis of light neutrino exchange and short-range mechanisms in 0νββ decay

Abstract

Neutrinoless double beta decay (0νββ) is a crucial test for lepton number violation. Observation of this process would have fundamental implications for neutrino physics, theories beyond the Standard Model and cosmology. Focusing on so-called short-range operators of 0νββ and their potential interplay with the standard light Majorana neutrino exchange, we present the first complete calculation of the relevant nuclear matrix elements, performed within the interacting boson model (IBM-2). Furthermore, we calculate the relevant phase space factors using exact Dirac electron wave functions, taking into account the finite nuclear size and screening by the electron cloud. The obtained numerical results are presented together with up-to-date limits on the standard mass mechanism and effective 0νββ short-range operators in the interacting boson model framework. Finally, we interpret the limits in the particle physics scenarios incorporating heavy sterile neutrinos, left-right symmetry and R-parity violating supersymmetry.