Search for flavour-changing neutral current interactions of the top quark and the Higgs boson in events with a pair of τ-leptons in pp collisions at √s = 13 TeV with the ATLAS detector

Anders, J.K.; Beck, H.P.; Chatterjee, M.; Ereditato, A.; Franconi, L.; Halser, L.; Haug, S.; Ilg, A.; Müller, R.; O'Neill, A.P.; Weber, M.S. (2023). Search for flavour-changing neutral current interactions of the top quark and the Higgs boson in events with a pair of τ-leptons in pp collisions at √s = 13 TeV with the ATLAS detector. Journal of High Energy Physics, 2023(6) Springer 10.1007/JHEP06(2023)155

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A search for flavour-changing neutral current (FCNC) tqH interactions involving a top quark, another up-type quark (q = u, c), and a Standard Model (SM) Higgs boson decaying into a τ -lepton pair (H → τ +τ −) is presented. The search is based on a dataset of pp collisions at √s = 13 TeV that corresponds to an integrated luminosity of 139 fb−1 recorded with the ATLAS detector at the Large Hadron Collider. Two processes are considered: single top quark FCNC production in association with a Higgs boson (pp → tH), and top quark pair production in which one of top quarks decays into W b and the other decays into qH through the FCNC interactions. The search selects events with two hadronically decaying τ -lepton candidates (τhad) or at least one τhad with an additional lepton (e, μ), as well as multiple jets. Event kinematics is used to separate signal from the background through a multivariate discriminant. A slight excess of data is observed with a significance of 2.3σ above the expected SM background, and 95% CL upper limits on the t → qH branching ratios are derived. The observed (expected) 95% CL upper limits set on the t → cH and t → uH branching ratios are 9.4 × 10−4 (4.8+2.2−1.4 × 10−4) and 6.9 × 10−4 (3.5+1.5−1.0 × 10−4), respectively. The corresponding combined observed (expected) upper limits on the dimension-6 operator Wilson coefficients in the effective tqH couplings are Ccφ < 1.35 (0.97) and Cuφ < 1.16 (0.82).

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Physics Institute > Laboratory for High Energy Physics (LHEP)
10 Strategic Research Centers > Albert Einstein Center for Fundamental Physics (AEC)

UniBE Contributor:

Anders, John Kenneth, Beck, Hans Peter, Chatterjee, Meghranjana, Ereditato, Antonio, Franconi, Laura, Halser, Lea, Haug, Sigve, Ilg, Armin, Müller, Roman, O'Neill, Aaron Paul, Weber, Michele

Subjects:

500 Science > 530 Physics

ISSN:

1029-8479

Publisher:

Springer

Language:

English

Submitter:

BORIS Import LHEP

Date Deposited:

14 Feb 2024 10:22

Last Modified:

30 Jun 2024 02:23

Publisher DOI:

10.1007/JHEP06(2023)155

Additional Information:

Kollaboration - Es sind nur die Berner Autor*innen namentlich erwaehnt; the ATLAS collaboration

Uncontrolled Keywords:

Flavour Changing Neutral Currents, Hadron-Hadron Scattering, Higgs Physics, Top Physics

BORIS DOI:

10.48350/191904

URI:

https://boris.unibe.ch/id/eprint/191904

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