Discovery prospects for the light charged Higgs boson decay to an off-shell top quark and a bottom quark at future high-energy colliders

Abstract The charged Higgs boson ( $$H^\pm $$ H ± ) with a mass below the top quark mass remains a viable possibility within the Type-I two-Higgs-doublet model under current constraints. While previous LHC searches have primarily focused on the $$H^\pm \rightarrow \tau ^\pm \nu $$ H ± → τ ± ν decay...

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Main Authors: Jinheung Kim, Soojin Lee, Prasenjit Sanyal, Jeonghyeon Song, Daohan Wang
Format: Article
Language:English
Published: SpringerOpen 2025-05-01
Series:European Physical Journal C: Particles and Fields
Online Access:https://doi.org/10.1140/epjc/s10052-025-14244-4
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author Jinheung Kim
Soojin Lee
Prasenjit Sanyal
Jeonghyeon Song
Daohan Wang
author_facet Jinheung Kim
Soojin Lee
Prasenjit Sanyal
Jeonghyeon Song
Daohan Wang
author_sort Jinheung Kim
collection DOAJ
description Abstract The charged Higgs boson ( $$H^\pm $$ H ± ) with a mass below the top quark mass remains a viable possibility within the Type-I two-Higgs-doublet model under current constraints. While previous LHC searches have primarily focused on the $$H^\pm \rightarrow \tau ^\pm \nu $$ H ± → τ ± ν decay mode, the decay channel into an off-shell top quark and a bottom quark, $$H^\pm \rightarrow t^*b$$ H ± → t ∗ b , is leading or subleading for $$H^\pm $$ H ± masses between 130 and 170 GeV. This study investigates the discovery potential of future colliders for this off-shell decay mode through pair-produced charged Higgs bosons decaying via $$H^+H^-\rightarrow t^*b\tau \nu \rightarrow bbjj\tau \nu $$ H + H - → t ∗ b τ ν → b b j j τ ν . We perform signal-to-background analyses at the HL-LHC and a prospective 100 TeV proton–proton collider, employing cut-flow strategies and the Boosted Decision Tree method. However, due to the softness of the b jets, signal significances fall below detection thresholds at these facilities. Extending our study to a multi-TeV muon collider (MuC), we demonstrate that a 3 TeV MuC achieves high signal significance, surpassing the $$5\sigma $$ 5 σ threshold with an integrated luminosity of 1 ab $$^{-1}$$ - 1 and a 10% background uncertainty. Specifically, for $$M_{H^\pm } = 130$$ M H ± = 130 , 150, and 170 GeV, the significances are 13.7, 13.5, and 6.06, respectively. In contrast, a 10 TeV MuC requires 10 ab $$^{-1}$$ - 1 to achieve similar results. Our findings highlight the critical role of the MuC in probing the new signal channel $$H^\pm \rightarrow t^*b$$ H ± → t ∗ b , offering a promising avenue for future charged Higgs boson searches involving off-shell top quarks.
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spelling doaj-art-b1c61375fe2f485482d3e873e37aee832025-08-20T01:51:36ZengSpringerOpenEuropean Physical Journal C: Particles and Fields1434-60522025-05-0185512310.1140/epjc/s10052-025-14244-4Discovery prospects for the light charged Higgs boson decay to an off-shell top quark and a bottom quark at future high-energy collidersJinheung Kim0Soojin Lee1Prasenjit Sanyal2Jeonghyeon Song3Daohan Wang4School of Physics, Korea Institute for Advanced StudyDepartment of Physics, Konkuk UniversityDepartment of Physics, Konkuk UniversityDepartment of Physics, Konkuk UniversityInstitute of High Energy Physics (HEPHY), Austrian Academy of Sciences (OeAW)Abstract The charged Higgs boson ( $$H^\pm $$ H ± ) with a mass below the top quark mass remains a viable possibility within the Type-I two-Higgs-doublet model under current constraints. While previous LHC searches have primarily focused on the $$H^\pm \rightarrow \tau ^\pm \nu $$ H ± → τ ± ν decay mode, the decay channel into an off-shell top quark and a bottom quark, $$H^\pm \rightarrow t^*b$$ H ± → t ∗ b , is leading or subleading for $$H^\pm $$ H ± masses between 130 and 170 GeV. This study investigates the discovery potential of future colliders for this off-shell decay mode through pair-produced charged Higgs bosons decaying via $$H^+H^-\rightarrow t^*b\tau \nu \rightarrow bbjj\tau \nu $$ H + H - → t ∗ b τ ν → b b j j τ ν . We perform signal-to-background analyses at the HL-LHC and a prospective 100 TeV proton–proton collider, employing cut-flow strategies and the Boosted Decision Tree method. However, due to the softness of the b jets, signal significances fall below detection thresholds at these facilities. Extending our study to a multi-TeV muon collider (MuC), we demonstrate that a 3 TeV MuC achieves high signal significance, surpassing the $$5\sigma $$ 5 σ threshold with an integrated luminosity of 1 ab $$^{-1}$$ - 1 and a 10% background uncertainty. Specifically, for $$M_{H^\pm } = 130$$ M H ± = 130 , 150, and 170 GeV, the significances are 13.7, 13.5, and 6.06, respectively. In contrast, a 10 TeV MuC requires 10 ab $$^{-1}$$ - 1 to achieve similar results. Our findings highlight the critical role of the MuC in probing the new signal channel $$H^\pm \rightarrow t^*b$$ H ± → t ∗ b , offering a promising avenue for future charged Higgs boson searches involving off-shell top quarks.https://doi.org/10.1140/epjc/s10052-025-14244-4
spellingShingle Jinheung Kim
Soojin Lee
Prasenjit Sanyal
Jeonghyeon Song
Daohan Wang
Discovery prospects for the light charged Higgs boson decay to an off-shell top quark and a bottom quark at future high-energy colliders
European Physical Journal C: Particles and Fields
title Discovery prospects for the light charged Higgs boson decay to an off-shell top quark and a bottom quark at future high-energy colliders
title_full Discovery prospects for the light charged Higgs boson decay to an off-shell top quark and a bottom quark at future high-energy colliders
title_fullStr Discovery prospects for the light charged Higgs boson decay to an off-shell top quark and a bottom quark at future high-energy colliders
title_full_unstemmed Discovery prospects for the light charged Higgs boson decay to an off-shell top quark and a bottom quark at future high-energy colliders
title_short Discovery prospects for the light charged Higgs boson decay to an off-shell top quark and a bottom quark at future high-energy colliders
title_sort discovery prospects for the light charged higgs boson decay to an off shell top quark and a bottom quark at future high energy colliders
url https://doi.org/10.1140/epjc/s10052-025-14244-4
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