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Search for tt[bar]H/A → tt[bar] tt[bar] production in proton-proton collisions √s=13TeV with the ATLAS detector

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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[bar]H/A), and with the H/A decaying into a tt[bar] pair. The full LHC Run 2 proton-proton collision data collected by the AT...

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Main Authors: Aad, Georges (Author) , Ackermann, Anke (Author) , Baltes, Lisa Marie (Author) , Bartels, Falk (Author) , Dittmeier, Sebastian (Author) , Dunford, Monica (Author) , Franchino, Silvia (Author) , Junkermann, Thomas (Author) , Mkrtchyan, Tigran (Author) , Sanfilippo, Lorenzo (Author) , Sauer, Christof (Author) , Schöning, André (Author) , Schultz-Coulon, Hans-Christian (Author) , Sothilingam, Varsiha (Author) , Stamen, Rainer (Author) , Starovoitov, Pavel (Author) , Vigani, Luigi (Author) , Wessels, Martin (Author) , Zinßer, Joachim (Author)
Corporate Author: ATLAS Collaboration (Author)
Format: Article (Journal)
Language:English
Published: 26 May 2025
In: The European physical journal. C, Particles and fields
Year: 2025, Volume: 85, Issue: 5, Pages: 1-36
ISSN:1434-6052
DOI:10.1140/epjc/s10052-025-14041-z
Online Access:Verlag, lizenzpflichtig, Volltext: https://doi.org/10.1140/epjc/s10052-025-14041-z
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Author Notes:ATLAS Collaboration*
Description
Summary: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[bar]H/A), and with the H/A decaying into a tt[bar] pair. The full LHC Run 2 proton-proton collision data collected by the ATLAS experiment is used, corresponding to an integrated luminosity of 139 fb -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[bar]+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[bar]H/A → tt[bar] tt[bar] 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[bar] tt[bar] cross-section, tan beta 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[bar] pair.
Item Description:Online veröffentlicht: 26. Mai 2025
Gesehen am 23.02.2026
Im Titel steht jeweils der zweite Buchstabe "t" mit einem Oberstrich
Im Titel steht der Buchstabe "s" unter dem Wurzelsymbol
*ATLAS Collaboration: G. Aad, A. Ackermann, L.M. Baltes, F. Bartels, S.J. Dittmeier, M. Dunford, S. Franchino, T. Junkermann, T. Mkrychyan, D.F. Rassloff, L. Sanfilippo, C. Sauer, A. Schoening, H.-C. Schultz-Coulon, V. Sothilingam, R. Stamen, P. Starovoitov, L. Vigani, M. Wessels, J. Zinsser [und sehr viele weitere Personen]
Physical Description:Online Resource
ISSN:1434-6052
DOI:10.1140/epjc/s10052-025-14041-z

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