Addendum to: QRPA uncertainties and their correlations in the analysis of neutrinoless double beta decay

TL;DR

This paper refines the estimation of nuclear matrix element uncertainties in neutrinoless double beta decay analysis using QRPA, compares experimental claims across different nuclei, and discusses issues in combining results from various experiments.

Contribution

It provides updated correlated uncertainty estimates for NMEs within QRPA and discusses the implications for interpreting experimental results across multiple nuclei.

Findings

QRPA-based NME uncertainties are consistent with recent calculations.

The claimed decay in Ge-76 is incompatible with negative results in Xe-136.

Recommendations are made for comparing and combining results from different nuclei.

Abstract

In a previous article [Phys. Rev. D 79, 053001 (2009)] we estimated the correlated uncertainties associated to the nuclear matrix elements (NME) of neutrinoless double beta decay (0 nu beta beta) within the quasiparticle random phase approximation (QRPA). Such estimates encompass recent independent calculations of NMEs, and can thus still provide a fair representation of the nuclear model uncertainties. In this context, we compare the claim of 0 nu beta beta decay in Ge-76 with recent negative results in Xe-136 and in other nuclei, and we infer the lifetime ranges allowed or excluded at 90% C.L. We also highlight some issues that should be addressed in order to properly compare and combine results coming from different 0 nu beta beta decay candidate nuclei.