Fermion mass hierarchies from vector-like families with an extended 2HDM and a possible explanation for the electron and muon anomalous magnetic moments

TL;DR

This paper proposes an extended 2HDM with vector-like families to explain fermion mass hierarchies and anomalous magnetic moments of electrons and muons, showing that Higgs scalar exchange can account for observed anomalies.

Contribution

It introduces a novel extended 2HDM with vector-like families that naturally generates fermion mass hierarchies and can explain electron and muon magnetic moment anomalies.

Findings

W exchange yields negligible contributions to magnetic moments.

Higgs scalar exchange can account for anomalies within experimental constraints.

Benchmark points indicate viable Higgs mass regions for explaining anomalies.

Abstract

We study an extended 2 Higgs doublet model (2HDM) in which the Standard Model (SM) Yukawa interactions are forbidden due to a global $U(1)^\prime$ symmetry, but may arise via mixing with vector-like families. In this model, the hierarchical structure of Yukawa couplings of quarks and leptons in the SM arises from the heavy masses of the fourth and fifth vector-like families. Within this model, we consider various non-standard contributions to the electron and muon anomalous magnetic moments. We first consider the $W$ exchange at one-loop level, consistent with the $\mu \rightarrow e \gamma$ constraint, and show that it yields a negligible contribution to both electron and muon anomalous magnetic moments. We then consider Higgs scalar exchange, together with vector-like leptons, at one-loop level and show that it is possible to have non-standard contributions to the electron and muon anomalous magnetic moments within the $1\sigma$ constraint of certain experiments. We present some benchmark points for both the muon and the electron anomalies, together with some numerical scans around these points, which indicate the mass regions of the Higgs scalars of the 2HDM in this scenario.