Analysis of Light Neutrino Exchange and Short-Range Mechanisms in $0\nu\beta\beta$ Decay

TL;DR

This paper provides a comprehensive calculation of nuclear matrix elements and phase space factors for neutrinoless double beta decay, analyzing both light neutrino exchange and short-range mechanisms, with implications for various particle physics models.

Contribution

It presents the first complete IBM-2 calculation of nuclear matrix elements for $0 uetaeta$, including short-range operators and phase space factors, and interprets experimental limits in new physics scenarios.

Findings

Calculated nuclear matrix elements within IBM-2 for $0 uetaeta$

Provided updated limits on effective operators and mass mechanisms

Analyzed implications for heavy sterile neutrinos, Left-Right symmetry, and R-parity violation

Abstract

Neutrinoless double beta decay ($0\nu\beta\beta$) 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. Focussing on so called short-range operators of $0\nu\beta\beta$ 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 wavefunctions, 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 $0\nu\beta\beta$ short-range operators in the IBM-2 framework. Finally, we interpret the limits in the particle physics scenarios incorporating heavy sterile neutrinos, Left-Right symmetry and R-parity violating supersymmetry.