Search for the Higgs boson decay to a Z boson and a photon in pp collisions at s=13 TeV and 13.6 TeV with the ATLAS detector

L.ZwalinskiThe ATLAS Collaboration

doi:10.1016/j.physletb.2026.140313

Search for the Higgs boson decay to a Z boson and a photon in pp collisions at s=13 TeV and 13.6 TeV with the ATLAS detector

L.ZwalinskiThe ATLAS Collaboration

Physics

Aix-Marseille Université
University of Bergen
University of Oklahoma
New York University Abu Dhabi
University of Göttingen
TU Dortmund University
United States Department of Energy
Southern Methodist University
Mohammed V University in Rabat
Tel Aviv University
New York University
National Institute for Nuclear Physics
Abdus Salam International Centre for Theoretical Physics
King's College London
Heidelberg University
Université de Savoie
AGH University of Krakow
SLAC National Accelerator Laboratory
University of Manchester
Northern Illinois University
Istanbul University
Rutherford Appleton Laboratory
University of California at Santa Cruz
The University of Chicago
Institute for High Energy Physics
Johannes Gutenberg University Mainz
Alexandru Ioan Cuza University of Iaşi
CERN
Azerbaijan National Academy of Sciences
Royal Holloway University of London
Zhengzhou University
University of Rome Tor Vergata
University of Valencia
University of Hassan II Casablanca
Lund University
Stony Brook University
Waseda University
University of Bonn
University of Würzburg
University of Victoria BC
University of Bern
Université Grenoble Alpes
University of Edinburgh
Oklahoma State University
Horia Hulubei National Institute of Physics and Nuclear Engineering
National Technical University of Athens

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Abstract

A search for the Higgs boson decay to a Z boson and a photon in the ℓℓ γ (ℓ=e,μ) final state is performed using pp collisions at s=13.6 TeV recorded with the ATLAS detector at the Large Hadron Collider during 2022–2024, corresponding to an integrated luminosity of 165 fb⁻¹. The signal yield, normalised to the Standard Model prediction, is measured to be μ=0.9_−0.6^+0.7, compatible with the expected value of μ=1.0±0.7. This corresponds to an observed (expected) signal significance of 1.4 (1.5) standard deviations under the background-only hypothesis. This result is combined with that of a similar search performed with 140 fb⁻¹ of s=13 TeV pp collisions to provide the best expected sensitivity to date to this rare decay, namely an observed (expected) signal strength of μ=1.3_−0.5^+0.6 (μ=1.0_−0.5^+0.6), corresponding to an observed (expected) significance of 2.5 (1.9) standard deviations. The measurement is consistent with the Standard Model expectation.

Original language	English
Article number	140313
Journal	Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Volume	876
DOIs	https://doi.org/10.1016/j.physletb.2026.140313
State	Published - May 2026

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10.1016/j.physletb.2026.140313

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@article{9ca219446e1b4b728d9adc70c3f6a37d,

title = "Search for the Higgs boson decay to a Z boson and a photon in pp collisions at s=13 TeV and 13.6 TeV with the ATLAS detector",

abstract = "A search for the Higgs boson decay to a Z boson and a photon in the ℓℓ γ (ℓ=e,μ) final state is performed using pp collisions at s=13.6 TeV recorded with the ATLAS detector at the Large Hadron Collider during 2022{\textendash}2024, corresponding to an integrated luminosity of 165 fb−1. The signal yield, normalised to the Standard Model prediction, is measured to be μ=0.9−0.6+0.7, compatible with the expected value of μ=1.0±0.7. This corresponds to an observed (expected) signal significance of 1.4 (1.5) standard deviations under the background-only hypothesis. This result is combined with that of a similar search performed with 140 fb−1 of s=13 TeV pp collisions to provide the best expected sensitivity to date to this rare decay, namely an observed (expected) signal strength of μ=1.3−0.5+0.6 (μ=1.0−0.5+0.6), corresponding to an observed (expected) significance of 2.5 (1.9) standard deviations. The measurement is consistent with the Standard Model expectation.",

author = "\{L.ZwalinskiThe ATLAS Collaboration\} and G. Aad and E. Aakvaag and B. Abbott and S. Abdelhameed and K. Abeling and Abicht, \{N. J.\} and Abidi, \{S. H.\} and M. Aboelela and A. Aboulhorma and H. Abramowicz and Y. Abulaiti and Acharya, \{B. S.\} and A. Ackermann and \{Adam Bourdarios\}, C. and L. Adamczyk and Addepalli, \{S. V.\} and Addison, \{M. J.\} and J. Adelman and A. Adiguzel and T. Adye and Affolder, \{A. A.\} and Y. Afik and Agaras, \{M. N.\} and A. Aggarwal and C. Agheorghiesei and F. Ahmadov and S. Ahuja and X. Ai and G. Aielli and A. Aikot and \{Ait Tamlihat\}, M. and B. Aitbenchikh and M. Akbiyik and {\AA}kesson, \{T. P.A.\} and Akimov, \{A. V.\} and D. Akiyama and Akolkar, \{N. N.\} and S. Aktas and Alberghi, \{G. L.\} and J. Albert and U. Alberti and P. Albicocco and Albouy, \{G. L.\} and S. Alderweireldt and Alegria, \{Z. L.\} and M. Aleksa and Aleksandrov, \{I. N.\} and C. Alexa and T. Alexopoulos and \{Mc Lean\}, \{C. A.\}",

note = "Publisher Copyright: Copyright {\textcopyright} 2026. Published by Elsevier B.V.",

year = "2026",

month = may,

doi = "10.1016/j.physletb.2026.140313",

language = "English",

volume = "876",

journal = "Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics",

issn = "0370-2693",

publisher = "Elsevier B.V.",

}

TY - JOUR

T1 - Search for the Higgs boson decay to a Z boson and a photon in pp collisions at s=13 TeV and 13.6 TeV with the ATLAS detector

AU - L.ZwalinskiThe ATLAS Collaboration

AU - Aad, G.

AU - Aakvaag, E.

AU - Abbott, B.

AU - Abdelhameed, S.

AU - Abeling, K.

AU - Abicht, N. J.

AU - Abidi, S. H.

AU - Aboelela, M.

AU - Aboulhorma, A.

AU - Abramowicz, H.

AU - Abulaiti, Y.

AU - Acharya, B. S.

AU - Ackermann, A.

AU - Adam Bourdarios, C.

AU - Adamczyk, L.

AU - Addepalli, S. V.

AU - Addison, M. J.

AU - Adelman, J.

AU - Adiguzel, A.

AU - Adye, T.

AU - Affolder, A. A.

AU - Afik, Y.

AU - Agaras, M. N.

AU - Aggarwal, A.

AU - Agheorghiesei, C.

AU - Ahmadov, F.

AU - Ahuja, S.

AU - Ai, X.

AU - Aielli, G.

AU - Aikot, A.

AU - Ait Tamlihat, M.

AU - Aitbenchikh, B.

AU - Akbiyik, M.

AU - Åkesson, T. P.A.

AU - Akimov, A. V.

AU - Akiyama, D.

AU - Akolkar, N. N.

AU - Aktas, S.

AU - Alberghi, G. L.

AU - Albert, J.

AU - Alberti, U.

AU - Albicocco, P.

AU - Albouy, G. L.

AU - Alderweireldt, S.

AU - Alegria, Z. L.

AU - Aleksa, M.

AU - Aleksandrov, I. N.

AU - Alexa, C.

AU - Alexopoulos, T.

AU - Mc Lean, C. A.

PY - 2026/5

Y1 - 2026/5

N2 - A search for the Higgs boson decay to a Z boson and a photon in the ℓℓ γ (ℓ=e,μ) final state is performed using pp collisions at s=13.6 TeV recorded with the ATLAS detector at the Large Hadron Collider during 2022–2024, corresponding to an integrated luminosity of 165 fb−1. The signal yield, normalised to the Standard Model prediction, is measured to be μ=0.9−0.6+0.7, compatible with the expected value of μ=1.0±0.7. This corresponds to an observed (expected) signal significance of 1.4 (1.5) standard deviations under the background-only hypothesis. This result is combined with that of a similar search performed with 140 fb−1 of s=13 TeV pp collisions to provide the best expected sensitivity to date to this rare decay, namely an observed (expected) signal strength of μ=1.3−0.5+0.6 (μ=1.0−0.5+0.6), corresponding to an observed (expected) significance of 2.5 (1.9) standard deviations. The measurement is consistent with the Standard Model expectation.

AB - A search for the Higgs boson decay to a Z boson and a photon in the ℓℓ γ (ℓ=e,μ) final state is performed using pp collisions at s=13.6 TeV recorded with the ATLAS detector at the Large Hadron Collider during 2022–2024, corresponding to an integrated luminosity of 165 fb−1. The signal yield, normalised to the Standard Model prediction, is measured to be μ=0.9−0.6+0.7, compatible with the expected value of μ=1.0±0.7. This corresponds to an observed (expected) signal significance of 1.4 (1.5) standard deviations under the background-only hypothesis. This result is combined with that of a similar search performed with 140 fb−1 of s=13 TeV pp collisions to provide the best expected sensitivity to date to this rare decay, namely an observed (expected) signal strength of μ=1.3−0.5+0.6 (μ=1.0−0.5+0.6), corresponding to an observed (expected) significance of 2.5 (1.9) standard deviations. The measurement is consistent with the Standard Model expectation.

UR - https://www.scopus.com/pages/publications/105038459310

U2 - 10.1016/j.physletb.2026.140313

DO - 10.1016/j.physletb.2026.140313

M3 - Article

AN - SCOPUS:105038459310

SN - 0370-2693

VL - 876

JO - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

JF - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

M1 - 140313

ER -

Search for the Higgs boson decay to a Z boson and a photon in pp collisions at s=13 TeV and 13.6 TeV with the ATLAS detector

Abstract

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