Eur. Phys. J. C (2025) 85: 500
https://doi.org/10.1140/epjc/s10052-025-14237-3

Regular Article - Theoretical Physics

Exploring vector-like top quark pair production via charged Higgs decays in multi-b-jet and opposite-sign dilepton final state at the LHC

¹ Polydisciplinary Faculty, Laboratory of Physics, Energy, Environment, and Applications, Cadi Ayyad University, B.P. 4162, Safi, Morocco
² Institute of Nuclear Physics, Polish Academy of Sciences, ul. Radzikowskiego 152, 31-342, Kraków, Poland
³ Laboratoire Interdisciplinaire de Recherche en Environnement, Management, Energie et Tourisme (LIREMET), ESTE, Cadi Ayyad University, B.P. 383, Essaouira, Morocco

^a mohammed.boukidi@ced.uca.ma

Received: 8 February 2025
Accepted: 25 April 2025
Published online: 8 May 2025

Abstract

We investigate the discovery prospects of a vector-like top partner (VLT) in the Type-II Two-Higgs-Doublet Model (2HDM-II) extended by a vector-like quark (VLQ) doublet (TB) at the 14 TeV Large Hadron Collider (LHC). In this work, the VLT is pair-produced via $pp\to T\overline{T}$ and predominantly decays through the cascade $T\to H^{+}b\to tbb$, with the top quark decaying leptonically. The resulting final state, comprising an opposite-sign lepton pair and multiple b-jets, offers a clean experimental signature. We evaluate the discovery significance as a function of the VLT and charged Higgs masses, integrated luminosity, and background systematic uncertainties. For $m_{H^{\pm }}=600$ GeV and 5% systematic uncertainty, a $5\sigma$ discovery is achievable for $m_T\lesssim 1300$ GeV with 300 fb$_{}^{-1}$ luminosity. At higher luminosities of 1000 and 3000 fb$_{}^{-1}$, the reach extends to 1500–1600 GeV, depending on the level of systematic uncertainty. While heavier $H^{\pm }$ masses reduce sensitivity, discovery remains attainable at high luminosity.