Measurement of the polarisation of single top quarks and antiquarks produced in the t-channel at root √s=13 TeV and bounds on the tWb dipole operator from the ATLAS experiment
Entity
UAM. Departamento de Física TeóricaPublisher
SpringerDate
2022-11-01Citation
10.1007/JHEP11(2022)040
Journal of High Energy Physics (JHEP) 2022.11 (2022): 40
ISSN
1126-6708 (print); 1029-8479 (online)DOI
10.1007/JHEP11(2022)040Editor's Version
https://doi.org/10.1007/JHEP11(2022)040Subjects
Hadron-Hadron Scattering; Top Physics; FísicaNote
Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiere, y los autores pertenecientes a la UAMRights
© 2022, The Author(s)Abstract
A simultaneous measurement of the three components of the top-quark and top-antiquark polarisation vectors in t-channel single-top-quark production is presented. This analysis is based on data from proton–proton collisions at a centre-of-mass energy of 13 TeV corresponding to an integrated luminosity of 139 fb−1, collected with the ATLAS detector at the LHC. Selected events contain exactly one isolated electron or muon, large missing transverse momentum and exactly two jets, one being b-tagged. Stringent selection requirements are applied to discriminate t-channel single-top-quark events from the background contributions. The top-quark and top-antiquark polarisation vectors are measured from the distributions of the direction cosines of the charged-lepton momentum in the top-quark rest frame. The three components of the polarisation vector for the selected top-quark event sample are Px′ = 0.01 ± 0.18, Py′ = −0.029 ± 0.027, Pz′ = 0.91 ± 0.10 and for the top-antiquark event sample they are Px′ = −0.02 ± 0.20, Py′ = −0.007 ± 0.051, Pz′ = 0.79 ± 0.16. Normalised differential cross-sections corrected to a fiducial region at the stable-particle level are presented as a function of the charged-lepton angles for top-quark and top-antiquark events inclusively and separately. These measurements are in agreement with Standard Model predictions. The angular differential cross-sections are used to derive bounds on the complex Wilson coefficient of the dimension-six OtW operator in the framework of an effective field theory. The obtained bounds are CtW ∈ [−0.9, 1.4] and CitW ∈ [−0.8, 0.2], both at 95% confidence leve
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Google Scholar:Aad, G.
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ATLAS Collaboration
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Álvarez Estévez, Manuel
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Barreiro Alonso, Fernando
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Calvente López, Sergio
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Camarero Muñoz, Daniel
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Peso Malagón, José del
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Glasman Kuguel, Claudia Beatriz
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Príncipe Martín, Miguel Ángel
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Terrón Cuadrado, Juan
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