Seesaw lepton masses and muon $g-2$ from heavy vector-like leptons

TL;DR

This paper introduces a model where heavy vector-like leptons and a seesaw mechanism generate the muon mass, and explains the muon g-2 anomaly through non-decoupling effects involving light Z' and dark Higgs bosons.

Contribution

It presents a novel seesaw model with vector-like leptons and a local U(1)' symmetry to explain muon mass and g-2, incorporating lepton-specific two Higgs doublets.

Findings

The model successfully accounts for the muon g-2 anomaly.

It constrains the parameter space using lepton flavor violation and collider data.

The scenario predicts light Z' and dark Higgs bosons relevant for experiments.

Abstract

We propose a model for the vector-like lepton to explain the small muon mass by a seesaw mechanism, based on lepton-specific two Higgs doublet models with a local $U(1)'$ symmetry. There is no bare muon mass for a nonzero $U(1)'$ charge of the leptophilic Higgs doublet, so the physical muon mass is generated due to the mixing between the vector-like lepton and the muon after the leptophilic Higgs doublet and the dark Higgs get VEVs. In this scenario, the non-decoupling effects of the vector-like lepton give rise to leading contributions to the muon $g-2$, thanks to the light $Z'$ and the light dark Higgs boson. We discuss various constraints on the model from lepton flavor violation, electroweak precision and Higgs data, as well as collider searches.