Search for tt¯H/A→tt¯tt¯ production in proton–proton collisions at s=13 TeV with the ATLAS detector

ATLAS Collaboration

doi:10.1140/epjc/s10052-025-14041-z

Search for tt¯H/A→tt¯tt¯ production in proton–proton collisions at s=13 TeV with the ATLAS detector

ATLAS Collaboration

iThemba Labs
Department of Physics
University of South Africa
University of Zululand
Cadi Ayyad University
Departamento de Física Teórica y del Cosmos
University of Granada
CERN
Columbia University
Demokritos National Centre for Scientific Research
University of Sheffield
Harvard University
University of Bologna
National Institute for Nuclear Physics
University of Belgrade
University of Siegen
Heidelberg University
CAS - Institute of High Energy Physics
University of Science and Technology of China
Shanghai Jiao Tong University
University of Michigan, Ann Arbor
Shandong University
University of Arizona
Nanjing University
Tsinghua University
University of Illinois at Urbana-Champaign
SLAC National Accelerator Laboratory
University of California at Santa Cruz
University of Washington
Université Paris-Saclay
Lawrence Berkeley National Laboratory
University College London
The University of Tokyo
CNRS

Research output: Contribution to journal › Article › peer-review

4 Scopus citations

Abstract

A search is presented for a heavy scalar (H) or pseudo-scalar (A) predicted by the two-Higgs-doublet models, where the H/A is produced in association with a top-quark pair (tt¯H/A), and with the H/A decaying into a tt¯ pair. The full LHC Run 2 proton–proton collision data collected by the ATLAS experiment is used, corresponding to an integrated luminosity of 139fb-1. Events are selected requiring exactly one or two opposite-charge electrons or muons. Data-driven corrections are applied to improve the modelling of the tt¯+jets background in the regime with high jet and b-jet multiplicities. These include a novel multi-dimensional kinematic reweighting based on a neural network trained using data and simulations. An H/A-mass parameterised graph neural network is trained to optimise the signal-to-background discrimination. In combination with the previous search performed by the ATLAS Collaboration in the multilepton final state, the observed upper limits on the tt¯H/A→tt¯tt¯ production cross-section at 95% confidence level range between 14 fb and 5.0 fb for an H/A with mass between 400 GeV and 1000 GeV, respectively. Assuming that both the H and A contribute to the tt¯tt¯ cross-section, tanβ values below 1.7 or 0.7 are excluded for a mass of 400 GeV or 1000 GeV, respectively. The results are also used to constrain a model predicting the pair production of a colour-octet scalar, with the scalar decaying into a tt¯ pair.

Original language	English
Article number	573
Journal	European Physical Journal C
Volume	85
Issue number	5
DOIs	https://doi.org/10.1140/epjc/s10052-025-14041-z
State	Published - May 2025

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@article{e96834581cce43fc99eb76be8d9bcc38,

title = "Search for tt¯H/A→tt¯tt¯ production in proton–proton collisions at s=13 TeV with the ATLAS detector",

abstract = "A search is presented for a heavy scalar (H) or pseudo-scalar (A) predicted by the two-Higgs-doublet models, where the H/A is produced in association with a top-quark pair (tt¯H/A), and with the H/A decaying into a tt¯ pair. The full LHC Run 2 proton–proton collision data collected by the ATLAS experiment is used, corresponding to an integrated luminosity of 139fb-1. Events are selected requiring exactly one or two opposite-charge electrons or muons. Data-driven corrections are applied to improve the modelling of the tt¯+jets background in the regime with high jet and b-jet multiplicities. These include a novel multi-dimensional kinematic reweighting based on a neural network trained using data and simulations. An H/A-mass parameterised graph neural network is trained to optimise the signal-to-background discrimination. In combination with the previous search performed by the ATLAS Collaboration in the multilepton final state, the observed upper limits on the tt¯H/A→tt¯tt¯ production cross-section at 95\% confidence level range between 14 fb and 5.0 fb for an H/A with mass between 400 GeV and 1000 GeV, respectively. Assuming that both the H and A contribute to the tt¯tt¯ cross-section, tanβ values below 1.7 or 0.7 are excluded for a mass of 400 GeV or 1000 GeV, respectively. The results are also used to constrain a model predicting the pair production of a colour-octet scalar, with the scalar decaying into a tt¯ pair.",

author = "\{ATLAS Collaboration\} and L. Zwalinski and W. Zou and O. Zormpa and Zorbas, \{T. G.\} and K. Zoch and A. Zoccoli and L. {\v Z}ivkovi{\'c} and M. Ziolkowski and J. Zinsser and Zimine, \{N. I.\} and K. Zhukov and X. Zhuang and Y. Zhu and Y. Zhu and X. Zhu and J. Zhu and Zhu, \{C. G.\} and Y. Zhou and Y. Zhou and Y. Zhou and N. Zhou and H. Zhou and B. Zhou and D. Zhong and Z. Zheng and X. Zheng and K. Zheng and J. Zheng and A. Zhemchugov and Z. Zhao and Z. Zhao and Y. Zhao and T. Zhao and H. Zhao and Z. Zhang and Z. Zhang and Z. Zhang and Y. Zhang and Y. Zhang and Y. Zhang and X. Zhang and X. Zhang and T. Zhang and S. Zhang and D. Tsybychev and G. Piacquadio and J. Jia and J. Hobbs and V. Dao and H. Arnold",

note = "Publisher Copyright: {\textcopyright} The Author(s) 2025.",

year = "2025",

month = may,

doi = "10.1140/epjc/s10052-025-14041-z",

language = "English",

volume = "85",

journal = "European Physical Journal C",

issn = "1434-6044",

number = "5",

}

TY - JOUR

T1 - Search for tt¯H/A→tt¯tt¯ production in proton–proton collisions at s=13 TeV with the ATLAS detector

AU - ATLAS Collaboration

AU - Zwalinski, L.

AU - Zou, W.

AU - Zormpa, O.

AU - Zorbas, T. G.

AU - Zoch, K.

AU - Zoccoli, A.

AU - Živković, L.

AU - Ziolkowski, M.

AU - Zinsser, J.

AU - Zimine, N. I.

AU - Zhukov, K.

AU - Zhuang, X.

AU - Zhu, Y.

AU - Zhu, X.

AU - Zhu, J.

AU - Zhu, C. G.

AU - Zhou, Y.

AU - Zhou, N.

AU - Zhou, H.

AU - Zhou, B.

AU - Zhong, D.

AU - Zheng, Z.

AU - Zheng, X.

AU - Zheng, K.

AU - Zheng, J.

AU - Zhemchugov, A.

AU - Zhao, Z.

AU - Zhao, Y.

AU - Zhao, T.

AU - Zhao, H.

AU - Zhang, Z.

AU - Zhang, Y.

AU - Zhang, X.

AU - Zhang, T.

AU - Zhang, S.

AU - Tsybychev, D.

AU - Piacquadio, G.

AU - Jia, J.

AU - Hobbs, J.

AU - Dao, V.

AU - Arnold, H.

PY - 2025/5

Y1 - 2025/5

N2 - A search is presented for a heavy scalar (H) or pseudo-scalar (A) predicted by the two-Higgs-doublet models, where the H/A is produced in association with a top-quark pair (tt¯H/A), and with the H/A decaying into a tt¯ pair. The full LHC Run 2 proton–proton collision data collected by the ATLAS experiment is used, corresponding to an integrated luminosity of 139fb-1. Events are selected requiring exactly one or two opposite-charge electrons or muons. Data-driven corrections are applied to improve the modelling of the tt¯+jets background in the regime with high jet and b-jet multiplicities. These include a novel multi-dimensional kinematic reweighting based on a neural network trained using data and simulations. An H/A-mass parameterised graph neural network is trained to optimise the signal-to-background discrimination. In combination with the previous search performed by the ATLAS Collaboration in the multilepton final state, the observed upper limits on the tt¯H/A→tt¯tt¯ production cross-section at 95% confidence level range between 14 fb and 5.0 fb for an H/A with mass between 400 GeV and 1000 GeV, respectively. Assuming that both the H and A contribute to the tt¯tt¯ cross-section, tanβ values below 1.7 or 0.7 are excluded for a mass of 400 GeV or 1000 GeV, respectively. The results are also used to constrain a model predicting the pair production of a colour-octet scalar, with the scalar decaying into a tt¯ pair.

AB - A search is presented for a heavy scalar (H) or pseudo-scalar (A) predicted by the two-Higgs-doublet models, where the H/A is produced in association with a top-quark pair (tt¯H/A), and with the H/A decaying into a tt¯ pair. The full LHC Run 2 proton–proton collision data collected by the ATLAS experiment is used, corresponding to an integrated luminosity of 139fb-1. Events are selected requiring exactly one or two opposite-charge electrons or muons. Data-driven corrections are applied to improve the modelling of the tt¯+jets background in the regime with high jet and b-jet multiplicities. These include a novel multi-dimensional kinematic reweighting based on a neural network trained using data and simulations. An H/A-mass parameterised graph neural network is trained to optimise the signal-to-background discrimination. In combination with the previous search performed by the ATLAS Collaboration in the multilepton final state, the observed upper limits on the tt¯H/A→tt¯tt¯ production cross-section at 95% confidence level range between 14 fb and 5.0 fb for an H/A with mass between 400 GeV and 1000 GeV, respectively. Assuming that both the H and A contribute to the tt¯tt¯ cross-section, tanβ values below 1.7 or 0.7 are excluded for a mass of 400 GeV or 1000 GeV, respectively. The results are also used to constrain a model predicting the pair production of a colour-octet scalar, with the scalar decaying into a tt¯ pair.

UR - https://www.scopus.com/pages/publications/105009301920

U2 - 10.1140/epjc/s10052-025-14041-z

DO - 10.1140/epjc/s10052-025-14041-z

M3 - Article

AN - SCOPUS:105009301920

SN - 1434-6044

VL - 85

JO - European Physical Journal C

JF - European Physical Journal C

IS - 5

M1 - 573

ER -

Search for tt¯H/A→tt¯tt¯ production in proton–proton collisions at s=13 TeV with the ATLAS detector

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