Cosmological signature and light Dark Matter in Dirac $L_\mu-L_\tau$ model

TL;DR

This paper explores a Dirac $L___ au$ gauge model with a new gauge boson and dark matter candidate, analyzing its parameter space, experimental constraints, and potential for detection in ongoing and future experiments.

Contribution

It introduces a Dirac neutrino framework with a gauged $L___ au$ symmetry, incorporating dark matter and studying its experimental viability and signatures.

Findings

Viable parameter space consistent with current bounds

Dark matter relic abundance achieved via resonance

Model predictions are testable in upcoming experiments

Abstract

We revisit an anomaly-free extension of the Standard Model (SM) $viz.$ gauged ${L_\mu-L_\tau}$ model in the Dirac framework, where the local $U(1)_{L_\mu-L_\tau}$ symmetry breaks and gives rise to a new gauge boson $Z'$ and corresponding gauge coupling $g_{\mu\tau}$. Three additional heavy vector-like fermions, three light right-handed neutrinos and two heavy singlet scalars are added to complete the model framework for Dirac neutrinos. Another singlet vector-like fermion is added with a new gauge charge, which serves as a viable DM candidate, and the correct relic abundance is obtained via the resonance effect. The parameter space is considered after satisfying the current bounds on $M_{Z'}$ and the gauge coupling $g_{\mu\tau}$. The influence of dark radiations coming from the additional light degrees of freedoms are studied in connection with the dark matter. After imposing all relevant theoretical and experimental constraints, the allowed parameter space is found to be highly restricted yet still accessible to ongoing and near-future experiments, rendering the scenario strongly predictive. Moreover, clear correlations among the relevant observables emerge throughout this study, making the model testable in current and future experimental searches.