High energy vector boson scattering in four-body final states to probe Higgs cubic, quartic, and HEFT interactions

Abstract We compute the energy scales of perturbative unitarity violation in various 2 → 4 vector boson scattering (VBS) processes and compare them to lower multiplicity processes. The final states include h 4, V L V L hh, and V L 4 $$ {V}_L^4 $$ , where V L represents the longitudinal mode of Z or...

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Bibliographic Details
Main Authors: Shameran Mahmud, Kohsaku Tobioka
Format: Article
Language:English
Published: SpringerOpen 2025-06-01
Series:Journal of High Energy Physics
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Online Access:https://doi.org/10.1007/JHEP06(2025)153
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Summary:Abstract We compute the energy scales of perturbative unitarity violation in various 2 → 4 vector boson scattering (VBS) processes and compare them to lower multiplicity processes. The final states include h 4, V L V L hh, and V L 4 $$ {V}_L^4 $$ , where V L represents the longitudinal mode of Z or W boson, and h the Higgs boson. We consider scenarios with modified cubic and quartic Higgs self-couplings, including those derived from the Standard Model Effective Field Theory (SMEFT), as well as scenarios involving derivative operators from Higgs Effective Field Theory (HEFT). Modified Higgs self-couplings typically lead to perturbative unitarity violation in at least the 2 → 3 VBS; however, the corresponding energy scales of unitarity violation are often very high. Our analysis reveals that, in the case of modified Higgs potentials, 2 → 4 processes exhibit significantly lower energy scales of unitarity violation compared to 2 → 3 processes. This, combined with the fact that the cross sections of 2 → 4 processes increase with energy, suggests they generate more signal events at high energies, s ̂ $$ \sqrt{\hat{s}} $$ ≳ 2 TeV, which could be achieved in future colliders. In contrast, for HEFT derivative interactions, higher multiplicity offers diminished benefits, as 2 → 4 cross sections are often smaller than those of related 2 → 3 processes within the valid energy range. This study shows that 2 → 4 VBS processes are particularly compelling for probing Higgs potential modification, including the cubic and quartic couplings, but are less advantageous when derivative interactions dominate.
ISSN:1029-8479