Systematical decomposition of dimension-11 short-range neutrinoless double beta decay operators

TL;DR

This paper classifies all tree-level UV completions of dimension-11 short-range operators contributing to neutrinoless double beta decay, identifying 28 viable diagrams and analyzing their experimental implications.

Contribution

It provides a systematic classification of all possible UV completions for short-range $0 uetaeta$ decay operators involving scalar and fermion mediators, including 61 new fields.

Findings

Current experiments constrain these models significantly.

Identified 8 topologies and 28 diagrams for UV completions.

Analyzed a representative model's impact on decay half-life and neutrino masses.

Abstract

Neutrinoless double beta decay ($0\nu\beta\beta$) may receive sizable contributions from short-range physics beyond the Standard Model. We present a systematical classification of all tree-level ultraviolet completions of the dimension-11 short-range $0\nu\beta\beta$ decay operators, renormalizable scenarios with scalar and fermion mediators are considered. We identify eight distinct topologies and twenty-eight viable diagrams, from which all consistent UV completions are generated by imposing Standard Model gauge invariance. All these models involve a total of 61 new fields beyond the Standard Model and they typically feature fractionally charged fermions and exotic bosons such as dileptons, diquarks, and leptoquarks. We further study a representative model without colored mediators and analyze its implications for the $0\nu\beta\beta$ decay half-life and light neutrino masses. We find that current and future $0\nu\beta\beta$ decay experiments impose stringent constraints. Our systematic decomposition provides a general framework for exploring exotic short-range contributions to $0\nu\beta\beta$ decay in future experiments.