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).

G. Aad, B. Abbott, D. C. Abbott, K. Abeling, S. H. Abidi, A. Aboulhorma, et al. (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), 0-56 [10.1007/jhep06(2023)155].

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

G. L. Alberghi;F. Alfonsi;M. Bindi;D. Boscherini;G. Cabras;G. Carratta;N. Cavalli;L. Clissa;S. De Castro;F. Fabbri;L. Fabbri;M. Franchini;A. Gabrielli;F. Lasagni Manghi;L. Massa;A. Polini;L. Rinaldi;M. Romano;C. Sbarra;A. Sbrizzi;N. Semprini-Cesari;M. Sioli;K. Todome;S. Valentinetti;M. Villa;C. Vittori;I. Vivarelli;A. Zoccoli;
2023

Abstract

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).
2023
G. Aad, B. Abbott, D. C. Abbott, K. Abeling, S. H. Abidi, A. Aboulhorma, et al. (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), 0-56 [10.1007/jhep06(2023)155].
G. Aad; B. Abbott; D. C. Abbott; K. Abeling; S. H. Abidi; A. Aboulhorma; H. Abramowicz; H. Abreu; Y. Abulaiti; A. C. Abusleme Hoffman; B. S. Acharya; ...espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/952777
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