# 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.

## Key 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.