Exploring $0\nu\beta\beta$ and Leptogenesis in the Alternative Left-Right Model

TL;DR

This paper explores neutrinoless double beta decay and leptogenesis in the Alternative Left-Right Model, highlighting unique features that lead to significant experimental signals and viable baryogenesis mechanisms.

Contribution

It introduces the ALRM with a Majorana right-handed neutrino and alternative mass generation, predicting observable $0 uetaeta$ signals and viable leptogenesis without fine tuning.

Findings

$0 uetaeta$ half-life around $3 imes 10^{26}$ years for moderate charged Higgs masses.

Significant CP violation from right-handed neutrino decay can produce correct baryon asymmetry.

Predictions are within reach of future experimental sensitivities.

Abstract

We investigate the possibility of neutrinoless double beta decay ($0\nu\beta\beta$) and leptogenesis within the Alternative Left-Right Model (ALRM). Unlike the usual left-right symmetric model, ALRM features a Majorana right-handed neutrino which does not carry any charge. Further, in this picture the down-type quark and the charged leptons receive mass through the additional left-handed scalar field, rather than the usual doublet. Together, these features conspire to generate significant contributions to the $0\nu\beta\beta$ through vector-scalar ($WH$) mediation. For moderate masses of the relevant charged Higgs boson ($M_{H_1^\pm}\sim 200$ GeV), the half-life of $T_{\frac{1}{2}}^{WH}$ is $\sim 3\times 10^{26}~{\rm yrs}$ for both the case of $^{76}$Ge and $^{136}$Xe, well within the sensitivity expected by future experiments. Invoking the resonant leptogenesis, CP violation arising from the right-handed neutrino decay could be the required order to generate the correct baryogenesis, $\epsilon\sim 10^{-6}$, for small Dirac phases and without any fine tuning.