Search for charged Higgs bosons through vector-like top quark pair production at the LHC

TL;DR

This study assesses the potential to discover charged Higgs bosons via vector-like top partner pair production at the 14 TeV LHC, focusing on fully hadronic final states with high b-jet multiplicity.

Contribution

It introduces a novel analysis strategy for detecting charged Higgs bosons through vector-like top quark pair production with detailed sensitivity projections.

Findings

Discovery potential up to 1300-1400 GeV for top partner mass at high luminosity

Higher systematic uncertainties significantly reduce discovery reach

Sensitivity decreases as charged Higgs mass increases, limiting detection prospects

Abstract

We investigate the discovery prospects for a vector-like top partner (VLT) in the Type-II Two-Higgs-Doublet Model (2HDM-II) extended by a vector-like quark doublet ($TB$) at the 14~TeV LHC. The study focuses on the pair production process $pp \to T\bar{T} \to bH^+\, \bar{b}H^- \to b(tb)\, \bar{b}(\bar{t}b)$, yielding fully hadronic final states characterized by high $b$-jet multiplicity. Two analysis strategies are employed, requiring at least four or five $b$-tagged jets (4$b$ and 5$b$), to exploit the signal topology. Assuming a charged Higgs mass of $m_{H^\pm} \sim 600$~GeV and a systematic uncertainty of $\delta = 5\%$, the 4$b$ channel enables discovery up to $m_T \sim 1200$~GeV at $\mathcal{L} = 300~\text{fb}^{-1}$, while the 5$b$ analysis extends the reach to $m_T \sim 1300$~GeV. At higher luminosities of 1000--3000~fb$^{-1}$, the 5$b$ strategy achieves discovery sensitivity up to $m_T \sim 1400$~GeV. The reach is significantly reduced as $m_{H^\pm}$ increases, due to the suppression of the $\text{BR}(T \to H^+ b)$: for $m_{H^\pm} \sim 1000$~GeV, discovery becomes unattainable across all luminosity and systematic uncertainty configurations. Sensitivity is also strongly impacted by systematic uncertainties: for $\delta = 10\%$ and $m_{H^\pm} < 1000$~GeV, discovery remains viable up to $m_T \sim 1200$~GeV in the 5$b$ analysis, while for $\delta = 20\%$, no discovery is achievable for $m_T \geq 1000$~GeV.