Lepton number and flavour violation in TeV-scale left-right symmetric theories with large left-right mixing

TL;DR

This paper investigates neutrinoless double beta decay within TeV-scale left-right symmetric models, analyzing how different mechanisms and interference effects influence decay rates, especially considering constraints from lepton flavor violation.

Contribution

It provides a detailed analysis of decay contributions in left-right models with type I and II seesaw dominance, highlighting scenarios with significant lambda- and eta-diagram effects.

Findings

Certain parameter regions enhance decay contributions from lambda- and eta-diagrams.

Heavy neutrinos at TeV scale can lead to sizable neutrinoless double beta decay signals.

Constraints from lepton flavor violation restrict viable parameter space.

Abstract

The various diagrams leading to neutrinoless double beta decay in the left-right symmetric model have different relative magnitudes, depending on the scale of new physics. Neutrinos acquire mass from both type I and/or type II seesaw terms, making an unambiguous analysis difficult. We study the half-life for double beta decay in the case of type II and type I dominance, in the former case including interference terms. If the heavy neutrinos of the type I seesaw model are at the TeV scale, certain processes can be enhanced. In particular, there are regions of parameter space in which the so-called lambda- and eta-diagrams can give sizable contributions to the half-life for the decay. We perform a detailed study of one such scenario, paying careful attention to constraints from lepton flavour violation.