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Role of angular observables in probing nonstandard $H Z Z$ couplings at an electron-proton collider

Indian Institute of Science Education and Research, Knowledge City, Sector 81, S. A. S. Nagar, Manauli PO 140306, Punjab, India

^*Contact author: pramodsharma.iiser@gmail.com
^†Contact author: ashivaji@iisermohali.ac.in

Phys. Rev. D 113, 015014 – Published 14 January, 2026

DOI: https://doi.org/10.1103/d66c-8jtg

Abstract

In this study, we explore various lab-frame angular observables at the Large Hadron-electron Collider (LHeC) to test their sensitivity to the most general structure of the Higgs ( $H$ ) to neutral weak boson ( $Z$ ) coupling ( $H Z Z$ ) via the process $e^{-} p \to e^{-} H j$ at the center of mass energy $\sqrt{s} \approx 1.3 TeV$ . The most general Lorentz structure of the $H Z Z$ coupling beyond the standard model is composed of two $C P$ -even ( $λ_{1 Z}$ and $λ_{2 Z}$ ) and one $C P$ -odd ( ${\tilde{λ}}_{Z}$ ) component. In a previous study, we investigated the absolute value of azimuthal correlation ( $| Δ ϕ |$ ) between the final state electron and the jet to derive constraints on the nonstandard $H Z Z$ couplings. This choice of observable is motivated by its potential to discriminate between $C P$ -odd and $C P$ -even couplings in the $e^{-} p \to ν_{e} H j$ process. Since the process $e^{-} p \to e^{-} H j$ has an electron in the final state, one can construct more angular observables. In addition to $| Δ ϕ |$ , we identify new angular observables: the sign-sensitive azimuthal correlation ( $Δ ϕ$ ) and the polar angle of the final state electron ( $θ$ ), which are suitable for constraining nonstandard $H Z Z$ coupling. Our analysis shows that these new angles improve the constraints on $λ_{2 Z}$ and ${\tilde{λ}}_{Z}$ in the range of 48%–67%. We also study the potential of the asymmetry in $Δ ϕ$ to constrain the parameters corresponding to the $C P$ -odd coupling.

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Phys. Rev. D 113, 015014– Published 14 January, 2026

Vol. 113, Iss. 1 — 1 January 2026

Received 4 June 2025
Accepted 22 December 2025

DOI: https://doi.org/10.1103/d66c-8jtg

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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Role of angular observables in probing nonstandard $H Z Z$ couplings at an electron-proton collider

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Role of angular observables in probing nonstandard HZZ couplings at an electron-proton collider

Abstract

Physics Subject Headings (PhySH)

Article Text

References (53)

Role of angular observables in probing nonstandard $H Z Z$ couplings at an electron-proton collider