The muon $g-2$ in an Aligned 2-Higgs Doublet Model with Right-Handed Neutrinos

Abstract

In this note, we show how one can attribute the anomaly currently present in the measurement of the anomalous magnetic moment of the muon ($a_\mu$) to the presence of an underlying Aligned 2-Higgs Doublet Model (A2HDM) with Right-Handed (RH) neutrinos, $\nu_R$. The effects of the latter scenario are driven by one and two-loop topologies wherein a very light CP-odd neutral Higgs state ($A$) contributes significantly to $a_\mu$. Over the region of parameter space of our new physics model which explains the aforementioned anomaly, also consistent with the most recent measurements of the electron anomalous magnetic moment ($a_e$), wherein the charged Higgs state $H^\pm$ plays a similar role, we predict an almost background-free hallmark signature of it, due to $H^\pm A$ production followed by Higgs boson decays yielding multi-$\tau$ final states, which can be already be searched for at the Large Hadron Collider (LHC).