Distinguishing the neutrinoless double beta decay mechanisms

TL;DR

This paper proposes that measuring the ratio of half-lives for neutrinoless double beta decay transitions to excited and ground states can help identify the dominant decay mechanism, emphasizing the need for precise nuclear matrix element calculations.

Contribution

It introduces a method to distinguish neutrinoless double beta decay mechanisms by analyzing decay to excited states, supported by theoretical and experimental considerations.

Findings

The half-life ratio can indicate the dominant decay mechanism.

High reliability nuclear matrix element calculations are essential.

Experimental studies of excited state transitions are strongly motivated.

Abstract

Many new neutrinoless double beta decay (0nbb) experiments are planned or in preparation. If the 0nbb-decay will be detected, the key issue will be what is the dominant mechanism of this process. By measuring only transitions to the ground state one can not distinguish among many of the 0nbb-decay mechanisms (the light and heavy Majorana neutrino exchange mechanisms, the trilinear R-parity breaking mechanisms etc.). We show that if the ratio of the 0nbb-decay half-lifes for transitions to the 0^+ first excited and ground states is determined both theoretically and experimentally, it might be possible to determine, which 0nbb-decay mechanisms is dominant. For that purpose the corresponding nuclear matrix elements have to be evaluated with high reliability. The present work is giving strong motivations for experimental studies of the 0nbb-decay transitions to the first excited 0^+ states of the final nuclei.