A new leading contribution to neutrinoless double-beta decay

TL;DR

This paper identifies a crucial missing short-range operator in neutrinoless double-beta decay calculations within chiral effective field theory, which could significantly impact experimental interpretations.

Contribution

It introduces a leading-order short-range operator into the decay transition operator, addressing a gap in current theoretical models.

Findings

Necessity of including a short-range operator for accurate decay predictions

Strategies proposed for determining the operator's finite part

Potential impact on nuclear matrix elements and experimental results

Abstract

Within the framework of chiral effective field theory we discuss the leading contributions to the neutrinoless double-beta decay transition operator induced by light Majorana neutrinos. Based on renormalization arguments in both dimensional regularization with minimal subtraction and a coordinate-space cutoff scheme, we show the need to introduce a leading-order short-range operator, missing in all current calculations. We discuss strategies to determine the finite part of the short-range coupling by matching to lattice QCD or by relating it via chiral symmetry to isospin-breaking observables in the two-nucleon sector. Finally, we speculate on the impact of this new contribution on nuclear matrix elements of relevance to experiment.