Constraints on lepton number violating short-range interactions from $|\Delta L|=2$ processes

TL;DR

This paper investigates short-range lepton number violating interactions through low-energy meson and tau decays, providing new constraints that complement neutrinoless double-beta decay results, especially for non-electron flavor couplings.

Contribution

It offers a comprehensive set of constraints on effective short-range LNV couplings from various low-energy processes, extending beyond neutrinoless double-beta decay.

Findings

Strong bounds on electron-electron LNV couplings from 0νββ decay.

Weaker but unique constraints on non-electron flavor LNV couplings.

Complementary limits from meson and tau decay processes.

Abstract

In this work we study the short-range contributions that induce effective lepton number violating (LNV) interactions. We obtain a full set of constraints on the effective short-range couplings from a large variety of low-energy $|\Delta L|= 2$ processes of pseudoscalar mesons $K, D, D_s, B$, and $\tau$-lepton. These constraints provide complementary and additional information to the one obtained from the neutrinoless double-$\beta$ ($0\nu\beta\beta$) decay. As expected, the bounds on electron-electron short-range couplings are the only ones that are strongly constrained by the $0\nu\beta\beta$ decay. Although weaker, LNV effective couplings with different flavours are not accessible to $0\nu\beta\beta$ decay and these can be probe by the $|\Delta L|= 2$ processes in consideration.