Hidden from View: Neutrino Masses, Dark Matter and TeV-Scale Leptogenesis in a Neutrinophilic 2HDM

TL;DR

This paper proposes a minimal extension of the Standard Model with additional scalars and fermions under a new gauge symmetry, enabling TeV-scale neutrino mass generation, dark matter, and leptogenesis, but with limited experimental accessibility.

Contribution

It introduces a neutrinophilic 2HDM with a $U(1)'$ gauge symmetry that achieves TeV-scale seesaw and leptogenesis with large Yukawa couplings.

Findings

TeV-scale seesaw mechanism achieved with specific charge assignments.

Model contains new TeV-scale particles with potential experimental signatures.

Most features remain inaccessible without additional lepton flavor symmetries.

Abstract

We consider a simple extension of the Standard Model providing dark matter and a TeV-scale seesaw mechanism that also allows for viable leptogenesis. In addition to the Standard Model degrees of freedom, the model contains a neutrinophilic Higgs doublet, a scalar singlet, and six singlet fermions (including three right-handed Majorana neutrinos) that are charged under a local $U(1)^\prime$ gauge symmetry. We show how the $U(1)^\prime$ charge assignments and the choice of scalar potential can lead to a TeV-scale seesaw mechanism and $\mathcal{O}(1)$ neutrino Yukawa couplings in a straightforward way. While this scenario has all the ingredients one would expect for significant experimental signatures, including several new TeV scale degrees of freedom, we find that most distinctive features associated with neutrino mass generation, leptogenesis and the dark sector are likely to remain inaccessible in the absence of additional lepton flavor symmetries.