Neutrinoless double beta decay: Electron angular correlation as a probe of new physics

TL;DR

This paper derives the angular distribution of electrons in neutrinoless double beta decay to help distinguish between different new physics models, providing a tool for experimental tests of beyond Standard Model theories.

Contribution

It presents a general derivation of electron angular correlations in neutrinoless double beta decay for various Lorentz-invariant theories, aiding model discrimination.

Findings

Angular distribution formulas for various models derived

Discrimination among theories based on angular correlations possible

Application to left-right symmetric model with current bounds

Abstract

The angular distribution of the final electrons in the so-called long range mechanism of the neutrinoless double beta decay ($0\nu2\beta$) is derived for the general Lorentz invariant effective Lagrangian. Possible theories beyond the SM are classified from their effects on the angular distribution, which could be used to discriminate among various particle physics models inducing $0\nu2\beta$ decays. However, additional input on the effective couplings will be required to single out the light Majorana-neutrino mechanism. Alternatively, measurements of the effective neutrino mass and angular distribution in $0\nu2\beta$ decays can be used to test the correlations among the parameters of the underlying physics models. This is illustrated for the left-right symmetric model, taking into account current phenomenological bounds.