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Searching for a charged Higgs boson in top-quark decays via the $W Z$ mode

Saiyad Ashanujjaman ^1,2,*, Andreas Crivellin ^3,4,†, Siddharth P. Maharathy^5,6,7,‡, and Bruce Mellado ^5,6,§

¹Institut für Theoretische Teilchenphysik, Karlsruhe Institute of Technology, Engesserstraße 7, D-76128 Karlsruhe, Germany
²Institut für Astroteilchenphysik, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany
³Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
⁴ICREA, Institució Catalana de Recerca i Estudis Avançats, Passeig de Lluís Companys 23, 08010 Barcelona, Spain
⁵School of Physics and Institute for Collider Particle Physics, University of the Witwatersrand, Johannesburg, Wits 2050, South Africa
⁶iThemba LABS, National Research Foundation, P.O. Box 722, Somerset West 7129, South Africa
⁷Indian Institute of Science Education and Research Pune, Dr. Homi Bhabha Road, Pune 411008, India

^*Contact author: saiyad.ashanujjaman@kit.edu
^†Contact author: andreas.crivellin@icrea.cat
^‡Contact author: siddharth.prasad.maharathy@cern.ch
^§Contact author: bmellado@mail.cern.ch

Phys. Rev. D 113, 115048 – Published 22 June, 2026

DOI: https://doi.org/10.1103/n2g2-gld5

Abstract

Top-quark decays are sensitive probes of light charged Higgs bosons ( $H^{\pm}$ ) due to the sizable $t \bar{t}$ production cross section at the LHC in conjunction with their distinct experimental signatures. While dedicated ATLAS and CMS searches considered only $H^{\pm}$ decays into $τ ν$ , $c s$ , or $c b$ for $m_{H^{\pm}} < m_{t}$ , the $W Z$ channel remains unexplored, despite being the dominant mode in $S U (2)_{L}$ triplet models. Since top-quark pair production with $t \to H^{\pm} b$ and $H^{\pm} \to W Z$ gives rise to $t \bar{t} Z$ -like signatures, we recast existing $t \bar{t} Z$ analyses to search for signs of charged Higgs bosons and set novel limits on the product of branching fractions $Br (t \to H^{\pm} b) \times Br (H^{\pm} \to W Z)$ . These constraints turn out to be at the sub-permille level, despite the observed $2 σ$ preference for a nonzero value. Interpreted within the hypercharge $Y = 0$ Higgs triplet model, this translates into a stringent constraint on the triplet Higgs vacuum expectation value of $v_{Δ} ≲ 2 GeV$ , which is stronger than those from the $c s, τ ν$ modes and even surpasses electroweak precision constraints from the $ρ$ parameter. Moreover, the $2 σ$ preference for a nonzero cross section further strengthens the cumulative case for a $\approx 152 GeV$ boson as suggested, in particular, by diphoton excesses.

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References (97)

P. W. Higgs, Broken symmetries, massless particles and gauge fields, Phys. Lett. 12, 132 (1964).
F. Englert and R. Brout, Broken symmetry and the mass of gauge vector mesons, Phys. Rev. Lett. 13, 321 (1964).
P. W. Higgs, Broken symmetries and the masses of gauge bosons, Phys. Rev. Lett. 13, 508 (1964).
G. S. Guralnik, C. R. Hagen, and T. W. B. Kibble, Global conservation laws and massless particles, Phys. Rev. Lett. 13, 585 (1964).
P. W. Higgs, Spontaneous symmetry breakdown without massless bosons, Phys. Rev. 145, 1156 (1966).
T. W. B. Kibble, Symmetry breaking in non-Abelian gauge theories, Phys. Rev. 155, 1554 (1967).
G. Aad et al. (ATLAS Collaboration), Observation of a new particle in the search for the standard model Higgs boson with the ATLAS detector at the LHC, Phys. Lett. B 716, 1 (2012).
S. Chatrchyan et al. (CMS Collaboration), Observation of a new boson at a mass of 125 GeV with the CMS experiment at the LHC, Phys. Lett. B 716, 30 (2012).
J. M. Langford (ATLAS and CMS Collaborations), Combination of Higgs measurements from ATLAS and CMS: Couplings and $k$ -framework, Proc. Sci. LHCP2020 (2021) 136.
, Combined measurements of Higgs boson production and decay at $\sqrt{s} = 13 TeV$ using up to $140 {fb}^{- 1}$ of data collected by the ATLAS Experiment, Report No. ATLAS-CONF-2025-006, 2025.
V. Silveira and A. Zee, Scalar phantoms, Phys. Lett. 161B, 136 (1985).
M. Pietroni, The electroweak phase transition in a nonminimal supersymmetric model, Nucl. Phys. B402, 27 (1993).
J. McDonald, Gauge singlet scalars as cold dark matter, Phys. Rev. D 50, 3637 (1994).
T. D. Lee, A theory of spontaneous T violation, Phys. Rev. D 8, 1226 (1973).
P. Fayet, Supergauge invariant extension of the Higgs mechanism and a model for the electron and its neutrino, Nucl. Phys. B90, 104 (1975).
P. Fayet, Spontaneously broken supersymmetric theories of weak, electromagnetic and strong interactions, Phys. Lett. 69B, 489 (1977).
H. E. Haber and G. L. Kane, The search for supersymmetry: Probing physics beyond the standard model, Phys. Rep. 117, 75 (1985).
J. E. Kim, Light pseudoscalars, particle physics and cosmology, Phys. Rep. 150, 1 (1987).
R. D. Peccei and H. R. Quinn, $C P$ conservation in the presence of instantons, Phys. Rev. Lett. 38, 1440 (1977).
N. Turok and J. Zadrozny, Electroweak baryogenesis in the two doublet model, Nucl. Phys. B358, 471 (1991).
D. A. Ross and M. J. G. Veltman, Neutral currents and the Higgs mechanism, Nucl. Phys. B95, 135 (1975).
W. Konetschny and W. Kummer, Nonconservation of total lepton number with scalar bosons, Phys. Lett. 70B, 433 (1977).
T. P. Cheng and L.-F. Li, Neutrino masses, mixings and oscillations in $S U (2) \times U (1)$ models of electroweak interactions, Phys. Rev. D 22, 2860 (1980).
G. Lazarides, Q. Shafi, and C. Wetterich, Proton lifetime and fermion masses in an $S O (10)$ model, Nucl. Phys. B181, 287 (1981).
J. Schechter and J. W. F. Valle, Neutrino masses in $S U (2) \times U (1)$ theories, Phys. Rev. D 22, 2227 (1980).
M. Magg and C. Wetterich, Neutrino mass problem and gauge hierarchy, Phys. Lett. 94B, 61 (1980).
R. N. Mohapatra and G. Senjanovic, Neutrino masses and mixings in gauge models with spontaneous parity violation, Phys. Rev. D 23, 165 (1981).
J. F. Gunion, R. Vega, and J. Wudka, Higgs triplets in the standard model, Phys. Rev. D 42, 1673 (1990).
T. G. Rizzo, Updated bounds on Higgs triplet vacuum expectation values and the tree level rho parameter from radiative corrections, Mod. Phys. Lett. A 6, 1961 (1991).
P. Chardonnet, P. Fayet, and P. Salati, Heavy triplet neutrinos as a new dark matter option, Nucl. Phys. B394, 35 (1993).
T. Blank and W. Hollik, Precision observables in $S U (2) \times U (1)$ models with an additional Higgs triplet, Nucl. Phys. B514, 113 (1998).
G. Aad et al. (ATLAS Collaboration), ATLAS searches for additional scalars and exotic Higgs boson decays with the LHC Run 2 dataset, Phys. Rep. 1116, 184 (2025).
G. Liu (CMS Collaboration), Searches for additional Higgs bosons at CMS, Proc. Sci. ICHEP2024 (2025) 052.
Y. Horii (ATLAS Collaboration), Searches for singly- and doubly-charged Higgs bosons in ATLAS, Proc. Sci. ICHEP2024 (2025) 070.
T. G. Rizzo, Top quark decay in models with Higgs triplets, Phys. Rev. D 41, 1504 (1990).
J. A. Coarasa Perez, J. Guasch, J. Sola, and W. Hollik, Top quark decay into charged Higgs boson in a general two Higgs doublet model: Implications for the Tevatron data, Phys. Lett. B 442, 326 (1998).
S. Bejar, J. Guasch, and J. Sola, Loop induced flavor changing neutral decays of the top quark in a general two Higgs doublet model, Nucl. Phys. B600, 21 (2001).
A. M. Sirunyan et al. (CMS Collaboration), Search for a light charged Higgs boson in the $H^{\pm} \to c s$ channel in proton-proton collisions at $\sqrt{s} = 13 TeV$ , Phys. Rev. D 102, 072001 (2020).
G. Aad et al. (ATLAS Collaboration), Search for a light charged Higgs boson in $t \to H^{\pm} b$ decays, with $H^{\pm} \to c s$ , in $p p$ collisions at $\sqrt{s} = 13 TeV$ with the ATLAS detector, Eur. Phys. J. C 85, 153 (2025).
G. Aad et al. (ATLAS Collaboration), Search for a light charged Higgs boson in $t \to H^{\pm} b$ decays, with $H^{\pm} \to c b$ , in the $lepton + jets$ final state in proton-proton collisions at $\sqrt{s} = 13 TeV$ with the ATLAS detector, J. High Energy Phys. 09 (2023) 004.
A. M. Sirunyan et al. (CMS Collaboration), Search for charged Higgs bosons in the $H^{\pm} \to τ^{\pm} ν_{τ}$ decay channel in proton-proton collisions at $\sqrt{s} = 13 TeV$ , J. High Energy Phys. 07 (2019) 142.
G. Aad et al. (ATLAS Collaboration), Search for charged Higgs bosons produced in top-quark decays or in association with top quarks and decaying via $H^{\pm} \to τ^{\pm} ν_{τ}$ in 13 TeV pp collisions with the ATLAS detector, Phys. Rev. D 111, 072006 (2025).
A. Crivellin and S. Iguro, Accumulating hints for flavor-violating Higgs bosons at the electroweak scale, Phys. Rev. D 110, 015014 (2024).
G. Coloretti, A. Crivellin, and S. Iguro, Searching for di-Higgs signatures of light charged scalars, J. High Energy Phys. 01 (2025) 016.
ALEPH, DELPHI, L3, OPAL Collaborations, and LEP Higgs Working Group, Search for charged Higgs bosons: Preliminary combined results using LEP data collected at energies up to 209 GeV, in 2001 Europhysics Conference on High Energy Physics (2001), arXiv:hep-ex/0107031.
H. Georgi and M. Machacek, Doubly charged Higgs bosons, Nucl. Phys. B262, 463 (1985).
M. S. Chanowitz and M. Golden, Higgs boson triplets with $M_{W} = M_{Z} \cos θ_{W}$ , Phys. Lett. 165B, 105 (1985).
K.-m. Cheung, R. J. N. Phillips, and A. Pilaftsis, Signatures of Higgs triplet representations at TeV $e^{+} e^{-}$ colliders, Phys. Rev. D 51, 4731 (1995).
K. Cheung and D. K. Ghosh, Triplet Higgs boson at hadron colliders, J. High Energy Phys. 11 (2002) 048.
E. Asakawa and S. Kanemura, The $H^{\pm} W^{\mp} Z^{0}$ vertex and single charged Higgs boson production via $W Z$ fusion at the large hadron collider, Phys. Lett. B 626, 111 (2005).
J. L. Diaz Cruz and D. A. Lopez Falcon, Testing models with nonminimal Higgs sector through the decay $t \to q + W Z$ , Phys. Rev. D 61, 051701 (2000).
G. Aad et al. (ATLAS Collaboration), Inclusive and differential cross-section measurements of $t \bar{t} Z$ production in pp collisions at $\sqrt{s} = 13 TeV$ with the ATLAS detector, including EFT and spin-correlation interpretations, J. High Energy Phys. 07 (2023) 163.
A. Hayrapetyan et al. (CMS Collaboration), Measurements of inclusive and differential cross sections for top quark production in association with a $Z$ boson in proton-proton collisions at $\sqrt{s} = 13 TeV$ , J. High Energy Phys. 02 (2024) 177.
A. Crivellin, Y. Fang, O. Fischer, S. Bhattacharya, M. Kumar, E. Malwa, B. Mellado, N. Rapheeha, X. Ruan, and Q. Sha, Accumulating evidence for the associated production of a new Higgs boson at the LHC, Phys. Rev. D 108, 115031 (2023).
S. Bhattacharya, G. Coloretti, A. Crivellin, S.-E. Dahbi, Y. Fang, M. Kumar, and B. Mellado, Growing excesses of new scalars at the electroweak scale, arXiv:2306.17209.
S. Bhattacharya, B. Lieberman, M. Kumar, A. Crivellin, Y. Fang, R. Mazini, and B. Mellado, Emerging excess consistent with a narrow resonance at 152 GeV in high-energy proton-proton collisions, arXiv:2503.16245.
S. von Buddenbrock, N. Chakrabarty, A. S. Cornell, D. Kar, M. Kumar, T. Mandal, B. Mellado, B. Mukhopadhyaya, R. G. Reed, and X. Ruan, Phenomenological signatures of additional scalar bosons at the LHC, Eur. Phys. J. C 76, 580 (2016).
S. von Buddenbrock, A. S. Cornell, A. Fadol, M. Kumar, B. Mellado, and X. Ruan, Multi-lepton signatures of additional scalar bosons beyond the standard model at the LHC, J. Phys. G 45, 115003 (2018).
S. Buddenbrock, A. S. Cornell, Y. Fang, A. Fadol Mohammed, M. Kumar, B. Mellado, and K. G. Tomiwa, The emergence of multi-lepton anomalies at the LHC and their compatibility with new physics at the EW scale, J. High Energy Phys. 10 (2019) 157.
S. von Buddenbrock, R. Ruiz, and B. Mellado, Anatomy of inclusive $t \bar{t} W$ production at hadron colliders, Phys. Lett. B 811, 135964 (2020).
G. Coloretti, A. Crivellin, S. Bhattacharya, and B. Mellado, Searching for low-mass resonances decaying into $W$ bosons, Phys. Rev. D 108, 035026 (2023).
S. Ashanujjaman, S. Banik, G. Coloretti, A. Crivellin, S. P. Maharathy, and B. Mellado, Explaining the $γ γ + X$ excesses at $\approx 151.5 GeV$ via the Drell-Yan production of a Higgs triplet, Phys. Lett. B 862, 139298 (2025).
A. Crivellin, S. Ashanujjaman, S. Banik, G. Coloretti, S. P. Maharathy, and B. Mellado, Growing evidence for a Higgs triplet, Chin. Phys. C 49, 053107 (2025).
S. Ashanujjaman, S. Banik, G. Coloretti, A. Crivellin, S. P. Maharathy, and B. Mellado, Anatomy of the real Higgs triplet model, J. High Energy Phys. 04 (2024) 003.
S. Banik, G. Coloretti, A. Crivellin, and B. Mellado, Uncovering new Higgses in the LHC analyses of differential $t \bar{t}$ cross sections, J. High Energy Phys. 01 (2023) 155.
G. Coloretti, A. Crivellin, and B. Mellado, Combined explanation of LHC multilepton, diphoton, and top-quark excesses, Phys. Rev. D 110, 073001 (2024).
M. Czakon and A. Mitov, top++: A program for the calculation of the top-pair cross-section at hadron colliders, Comput. Phys. Commun. 185, 2930 (2014).
J. Alwall, R. Frederix, S. Frixione, V. Hirschi, F. Maltoni, O. Mattelaer, H. S. Shao, T. Stelzer, P. Torrielli, and M. Zaro, The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations, J. High Energy Phys. 07 (2014) 079.
R. Frederix, S. Frixione, V. Hirschi, D. Pagani, H. S. Shao, and M. Zaro, The automation of next-to-leading order electroweak calculations, J. High Energy Phys. 07 (2018) 185; 11 (2021) 085(E).
R. D. Ball et al. (NNPDF Collaboration), Parton distributions from high-precision collider data, Eur. Phys. J. C 77, 663 (2017).
S. Frixione, B. Fuks, V. Hirschi, K. Mawatari, H.-S. Shao, P. A. Sunder, and M. Zaro, Automated simulations beyond the standard model: Supersymmetry, J. High Energy Phys. 12 (2019) 008.
C. Bierlich et al., A comprehensive guide to the physics and usage of pythia 8.3, SciPost Phys. Codebases 2022, 8 (2022).
J. Bellm et al., herwig7.0/herwig++ 3.0 release note, Eur. Phys. J. C 76, 196 (2016).
T. Sjöstrand, S. Ask, J. R. Christiansen, R. Corke, N. Desai, P. Ilten, S. Mrenna, S. Prestel, C. O. Rasmussen, and P. Z. Skands, An introduction to pythia 8.2, Comput. Phys. Commun. 191, 159 (2015).
V. Khachatryan et al. (CMS Collaboration), Event generator tunes obtained from underlying event and multiparton scattering measurements, Eur. Phys. J. C 76, 155 (2016).
M. Cacciari, G. P. Salam, and G. Soyez, The anti- $k_{t}$ jet clustering algorithm, J. High Energy Phys. 04 (2008) 063.
M. Cacciari, G. P. Salam, and G. Soyez, fastjet user manual, Eur. Phys. J. C 72, 1896 (2012).
H. Bahl, R. Kumar, and G. Weiglein, Impact of interference effects on Higgs-boson searches in the di-top final state at the LHC, J. High Energy Phys. 05 (2025) 098.
P. Fileviez Perez, H. H. Patel, and A. D. Plascencia, On the $W$ mass and new Higgs bosons, Phys. Lett. B 833, 137371 (2022).
T. G. Rizzo, Kinetic mixing, dark Higgs triplets, and MW, Phys. Rev. D 106, 035024 (2022).
J.-W. Wang, X.-J. Bi, P.-F. Yin, and Z.-H. Yu, Electroweak dark matter model accounting for the CDF $W$ -mass anomaly, Phys. Rev. D 106, 055001 (2022).
Y. Cheng, X.-G. He, F. Huang, J. Sun, and Z.-P. Xing, Electroweak precision tests for triplet scalars, Nucl. Phys. B989, 116118 (2023).
H. Song, X. Wan, and J.-H. Yu, Custodial symmetry violation in scalar extensions of the standard model, Chin. Phys. C 47, 103103 (2023).
T. Aaltonen et al. (CDF Collaboration), High-precision measurement of the $W$ boson mass with the CDF II detector, Science 376, 170 (2022).
J. de Blas, M. Ciuchini, E. Franco, A. Goncalves, S. Mishima, M. Pierini, L. Reina, and L. Silvestrini, Global analysis of electroweak data in the standard model, Phys. Rev. D 106, 033003 (2022).
E. Bagnaschi, J. Ellis, M. Madigan, K. Mimasu, V. Sanz, and T. You, SMEFT analysis of $m_{W}$ , J. High Energy Phys. 08 (2022) 308.
M. Chabab, M. C. Peyranère, and L. Rahili, Probing the Higgs sector of $Y = 0$ Higgs triplet model at LHC, Eur. Phys. J. C 78, 873 (2018).
J. Butterworth, H. Debnath, P. Fileviez Perez, and F. Mitchell, Custodial symmetry breaking and Higgs boson signatures at the LHC, Phys. Rev. D 109, 095014 (2024).
S. Navas et al. (Particle Data Group), Review of particle physics, Phys. Rev. D 110, 030001 (2024).
S.-Y. Ma, X.-D. Huang, X.-C. Zheng, and X.-G. Wu, Precise determination of the bottom-quark on-shell mass using its four-loop relation to the $\bar{MS}$ -scheme running mass, Chin. Phys. Lett. 41, 101201 (2024).
J. Aparisi et al., $m_{b}$ at $m_{H}$ : The running bottom quark mass and the Higgs boson, Phys. Rev. Lett. 128, 122001 (2022).
A. Czarnecki and S. Davidson, QCD corrections to the charged Higgs decay of a heavy quark, Phys. Rev. D 48, 4183 (1993).
A. Czarnecki and K. Melnikov, Two loop QCD corrections to top quark width, Nucl. Phys. B544, 520 (1999).
K. G. Chetyrkin, R. Harlander, T. Seidensticker, and M. Steinhauser, Second order QCD corrections to $Γ (\bar{t} W b)$ . Phys. Rev. D 60, 114015 (1999).
L.-B. Chen, H. T. Li, J. Wang, and Y. Wang, Analytic result for the top-quark width at next-to-next-to-leading order in QCD, Phys. Rev. D 108, 054003 (2023).
S. Amoroso et al. (LHC-TeV MW Working Group), Compatibility and combination of world W-boson mass measurements, Eur. Phys. J. C 84, 451 (2024).
A. Tumasyan et al. (CMS Collaboration), Search for direct pair production of supersymmetric partners of $τ$ leptons in the final state with two hadronically decaying $τ$ leptons and missing transverse momentum in proton-proton collisions at $\sqrt{s} = 13 TeV$ , Phys. Rev. D 108, 012011 (2023).

Phys. Rev. D 113, 115048– Published 22 June, 2026

Vol. 113, Iss. 11 — 1 June 2026

Received 10 September 2025
Accepted 27 May 2026

DOI: https://doi.org/10.1103/n2g2-gld5

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP³.

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Searching for a charged Higgs boson in top-quark decays via the $W Z$ mode

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Searching for a charged Higgs boson in top-quark decays via the WZ mode

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References (97)

Searching for a charged Higgs boson in top-quark decays via the $W Z$ mode