Searching for charged Higgs bosons via $e^+ e^- \to H^\pm W^\mp S$ at the ILC

TL;DR

This paper explores the potential to detect light charged Higgs bosons at the ILC within the type-X 2HDM framework, focusing on specific production and decay channels that could reveal new physics beyond the Standard Model.

Contribution

It introduces a novel analysis of $e^+ e^- o H^b W^b S$ processes at the ILC, highlighting their sensitivity to the Higgs mixing angle and potential for discovery.

Findings

Event rates for $e^+ e^- o H^b W^b S$ can surpass those of $H^+ H^-$ production.

The $[ au au][ au au] WW$ final state is detectable at the ILC with 500 GeV and 500 fb$^{-1}$.

Light charged Higgs bosons are consistent with current flavor and collider data.

Abstract

We investigate the phenomenology of the charged Higgs boson at the International Linear Collider (ILC) within the framework of the type-X Two-Higgs Doublet Model (2HDM), where a light charged Higgs boson, with a mass around 200 GeV or even smaller than top quark mass, is still being consistent with flavor physics data as well as with the colliders experimental data. In the theoretically and experimentally allowed parameter space, the $e^+ e^- \to H^\pm W^\mp S$ (with $S = H, A$) production processes can yield signatures with event rates larger than those from $e^+ e^- \to H^+ H^-$ and offer sensitivity to the Higgs mixing parameter $\sin(\beta-\alpha)$. We consider the bosonic $H^\pm \to W^\pm S$ decays, where the neutral scalar $S$ further decays into a pair of tau leptons. We show, through a detector-level Monte Carlo analysis, that the resulting $[\tau\tau][\tau\tau] WW$ final state could be seen at the ILC with at least 500 GeV center-of-mass energy and 500 fb$^{-1}$ of luminosity.