Muon $g-2$ in two Higgs doublet models with vectorlike leptons

TL;DR

This paper investigates how two Higgs doublet models extended with vectorlike leptons can account for the muon g-2 anomaly, showing that certain models can produce large enough contributions to explain the discrepancy.

Contribution

It provides detailed predictions for muon g-2 contributions in two specific two Higgs doublet models with vectorlike leptons, highlighting scenarios with significant enhancements.

Findings

Z2-symmetric model can generate contributions two orders of magnitude larger than the standard model.

Supersymmetry-motivated couplings typically lead to smaller contributions due to cancellations.

Charged Higgs boson contributions can fully explain the muon g-2 anomaly.

Abstract

We calculate contributions to the anomalous magnetic moment of the muon from heavy neutral and charged Higgs bosons and new leptons in two Higgs doublet models extended by vectorlike leptons. We present detailed predictions of two models with type-II couplings to standard model fermions, motivated by a $Z_2$ symmetry and supersymmetry. In addition, we compare the results with the standard model extended by vectorlike leptons. We find that the model motivated by a $Z_{2}$ symmetry can generate much larger contributions to the magnetic moment compared to the standard model, even by two orders of magnitude due to $\tan^{2}\beta$ enhancement, while satisfying current constraints. As a consequence, the standard model explanation of the anomaly requires much larger corrections to muon couplings making this model easier to probe at future precision machines. Additionally, we find that the model with couplings motivated by supersymmetry typically leads to much smaller contributions to the anomaly as a result of cancellations. However, we identify interesting scenarios where contributions from the charged Higgs boson can fully explain the anomaly.