Single Production of a Vector-Like Top as a Probe of Charged Higgs Bosons at a Muon-Proton Collider

Abstract

We investigate the discovery prospects for a vector-like top partner ($T$) within the Type-II Two-Higgs-Doublet Model (2HDM-II) at future high-energy $\mu p$ colliders. The analysis focuses on the charged Higgs decay mode $\mu^+ p \to \nu_\mu\, \bar{b}T \to \nu_\mu\, \bar{b}H^+b$, with the subsequent decay $H^+\to t\bar{b}$ yielding a final state with multiple $b$-jets and a charged lepton. A detailed detector-level simulation is carried out for benchmark configurations with charged Higgs masses around 600-650~GeV and vector-like top masses in the range $m_T \simeq 1.0$-$1.8$~TeV. For an integrated luminosity of 100~fb$^{-1}$, discovery significances above $5\sigma$ are obtained across several benchmark points, remaining robust against systematic uncertainties up to 20\%. At higher luminosities of 234~fb$^{-1}$, the sensitivity exceeds $10\sigma$ for the lightest benchmarks and stays above $5\sigma$ even in the presence of 30\% systematics.