Observability of 2HDM charged Higgs boson in a misaligned scenario

TL;DR

This paper evaluates the potential of future lepton colliders to observe the charged Higgs boson in a misaligned 2HDM scenario, showing they can probe regions beyond HL-LHC reach with significant sensitivity.

Contribution

It provides the first detailed analysis of lepton collider prospects for charged Higgs detection in a misaligned 2HDM, focusing on the $H^{b} o W^{b}h_{125}$ decay channel.

Findings

Lepton colliders can probe parameter space beyond HL-LHC reach.

Significance exceeds 2σ and 5σ in certain mass and tanβ ranges.

Optimal sensitivity for $350 < m_{H^{b}} < 450$ GeV and $ an eta \u2265 4$.

Abstract

The large hadron collider precision measurement of $h_{125}$ properties suggests that a misaligned two Higgs doublet model type 1 is preferred among other types of the model. In this analysis, a lepton collider potential for charged Higgs boson observation is evaluated and compared with HL-LHC expectations. We focus on $H^{\pm} \to W^{\pm}h_{125}$ decay which is exclusively activated in misalignment scenario. An event analysis including fast detector simulation is performed and it is shown that some parts of the parameter space which are out of HL-LHC reach can be probed by a high energy lepton collider with signal significance exceeding $2\sigma$ and $5\sigma$ for exclusion or discovery. The region with highest sensitivity is in the middle range charged Higgs boson mass, i.e., $350 < m_{H^{\pm}} <450$ GeV and $\tan \beta \gtrsim4$ at non-zero $\cos(\beta-\alpha)$ values.