Muon $g-2$ in a 2HDM assisted by inert scalars: probing at the ILC

TL;DR

This paper investigates a Two-Higgs Doublet Model with inert scalars to explain the muon g-2 anomaly and assesses the ILC's potential to discover a heavy pseudoscalar particle through specific leptonic signals.

Contribution

It demonstrates that the ILC can effectively probe heavier pseudoscalars in the 2HDM with inert scalars, surpassing the LHC's capabilities.

Findings

ILC can discover pseudoscalars up to 400 GeV at 5σ significance.

Beam polarization enhances detection sensitivity.

ILC outperforms LHC in probing this model.

Abstract

A Two-Higgs doublet model (2HDM) can predict the observed muon $g-2$ for an appropriately light pseudoscalar that now faces tight constraints. However, It was shown in past that augmenting the 2HDM by an additional inert doublet can lead to an explanation to the muon $g-2$ anomaly for a much heavier pseudoscalar. In this study, we probe such a framework at the proposed International Linear Collider (ILC) using beam polarization for $\sqrt{s}$ = 1 TeV. Using multivariate techniques, we analyse the signals $e^+ e^- \rightarrow \tau^+ \tau^- +$ missing transverse energy and $e^+ e^- \rightarrow \mu^+ \mu^- + $ missing transverse energy in the lepton- and muon-specific versions of the framework respectively. Our analysis reveals that the $e^+ e^-$ machine operating at a 3000 fb$^{-1}$ luminosity predicts a 5$\sigma$ discovery of a pseudoscalar as heavy as 400 GeV. Comparing with the previous study, it is concluded that the ILC is a much more potent machine than the LHC in this regard.