Two-loop QCD corrections to CP-even Higgs boson decays into Vγ in the Type-I Two-Higgs-Doublet Model
Abstract
We investigate the QCD corrections to the loop-induced decays of the heavy CP-even Higgs boson, H → Vγ (V = Z, γ), within the framework of the Type-I Two-Higgs-Doublet Model (THDM). Owing to the similarity of the underlying loop topologies, the two decay channels exhibit closely correlated behaviour. After imposing relevant phenomenological constraints, we evaluate the decay widths for 5000 viable parameter points at next-to-leading order (NLO) in QCD under the alignment limit. The H→γγ width exceeds that of H→ Zγ by roughly a factor of four. Both are dominated by the top-quark loop: the W contribution vanishes in the alignment limit, and the charged-Higgs loop is suppressed throughout most of the viable parameter region. The corrections exhibit a pronounced dependence on the heavy Higgs boson mass mH, attaining a maximum in the vicinity of the tt̅ production threshold. To elucidate the individual parameter dependences, dedicated benchmark scenarios are analysed, revealing that the decay widths diminish monotonically with increasing tanβ while growing with mH. The QCD corrections for both decay modes typically span approximately −20% to +20%, with larger corrections in the non-alignment scenario: in the H→γγ channel they reach up to +38% at large tanβ, and in the H→ Zγ channel they cross zero to become positive. The CP selection rule forces the tt̅ pair into a P-wave configuration at threshold, which strongly suppresses the Coulomb corrections and secures the perturbative stability of the fixed-order prediction. A comparison with ATLAS limits shows that current data do not yet constrain the parameter space, whereas the 𝒪(15%) NLO corrections may become relevant for interpreting exclusion bounds at the HL-LHC.
Related
- Electroweak corrections to the SM-like Higgs boson decays and the Higgs trilinear coupling in the real Higgs triplet model
- Flavor-Violating Higgs and Top Decays in the Type 1B Flavorful Two-Higgs-Doublet Model with a Twist
- Parton-shower and fixed-order QCD effects in Higgs boson production in weak-boson fusion and its decays to bottom quarks
- Three-loop QCD corrections to the production of a Higgs boson and a jet
- Dark photons in exotic Higgs boson decays at FCC-ee
BibTeX
@misc{qu2026twoloop,
title = {{Two-loop QCD corrections to $CP$-even Higgs boson decays into $Vγ$ in the Type-I Two-Higgs-Doublet Model}},
author = {Lin-Qiao Qu and Zhong-Yuan Liu and Peng-Fei Duan and Yu Zhang and Wei-Long Duan},
howpublished = {arXiv},
year = {2026},
month = aug,
doi = {10.48550/arxiv.2608.30436},
eprint = {2608.30436},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.30436},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Two-loop QCD corrections to CP-even Higgs boson decays into Vγ in the Type-I Two-Higgs-Doublet Model
AU - Lin-Qiao Qu
AU - Zhong-Yuan Liu
AU - Peng-Fei Duan
AU - Yu Zhang
AU - Wei-Long Duan
PY - 2026
DA - 2026/08/31
PB - arXiv
DO - 10.48550/arxiv.2608.30436
UR - https://arxiv.org/abs/2608.30436
AB - We investigate the QCD corrections to the loop-induced decays of the heavy CP-even Higgs boson, H → Vγ (V = Z, γ), within the framework of the Type-I Two-Higgs-Doublet Model (THDM). Owing to the similarity of the underlying loop topologies, the two decay channels exhibit closely correlated behaviour. After imposing relevant phenomenological constraints, we evaluate the decay widths for 5000 viable parameter points at next-to-leading order (NLO) in QCD under the alignment limit. The H→γγ width exceeds that of H→ Zγ by roughly a factor of four. Both are dominated by the top-quark loop: the W contribution vanishes in the alignment limit, and the charged-Higgs loop is suppressed throughout most of the viable parameter region. The corrections exhibit a pronounced dependence on the heavy Higgs boson mass m_H, attaining a maximum in the vicinity of the tt̅ production threshold. To elucidate the individual parameter dependences, dedicated benchmark scenarios are analysed, revealing that the decay widths diminish monotonically with increasing tanβ while growing with m_H. The QCD corrections for both decay modes typically span approximately −20% to +20%, with larger corrections in the non-alignment scenario: in the H→γγ channel they reach up to +38% at large tanβ, and in the H→ Zγ channel they cross zero to become positive. The CP selection rule forces the tt̅ pair into a P-wave configuration at threshold, which strongly suppresses the Coulomb corrections and secures the perturbative stability of the fixed-order prediction. A comparison with ATLAS limits shows that current data do not yet constrain the parameter space, whereas the 𝒪(15%) NLO corrections may become relevant for interpreting exclusion bounds at the HL-LHC.
ER -