Search for top-quark decays t→Hq with 36 fb−1 of pp collision data at s√=13 TeV with the ATLAS detector Aaboud, M. Aguilar Saavedra, Juan Antonio Atlas Collaboration A search for flavour-changing neutral current decays of a top quark into an up-type quark (q=u,c) and the Standard Model Higgs boson, t→Hq, is presented. The search is based on a dataset of pp collisions at s√=13 TeV recorded in 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider and corresponds to an integrated luminosity of 36.1 fb−1. Two complementary analyses are performed that search for top-quark pair events in which one top quark decays into Wb and the other top quark decays into Hq, and target the H→bb¯ and H→τ+τ− decay modes, respectively. The high multiplicity of b-quark jets, or the presence of hadronically decaying τ-leptons, are exploited in the two analyses respectively. Multivariate techniques are used to separate the signal from the background, which is dominated by top-quark pair production. No significant excess of events above the background expectation is found, and 95% CL upper limits on the t→Hq branching ratios are derived. The combination of these searches with ATLAS searches in diphoton and multilepton final states yields observed (expected) 95% CL upper limits on the t→Hc and t→Hu branching ratios of 1.1×10−3 (8.3×10−4) and 1.2×10−3 (8.3×10−4), respectively. The corresponding combined observed (expected) upper limits on the |λtcH| and |λtuH| couplings are 0.064 (0.055) and 0.066 (0.055), respectively. 2020-03-05T08:56:46Z 2020-03-05T08:56:46Z 2019-05-21 info:eu-repo/semantics/article Álvarez Piqueras, D., Aparisi, P., Bailey, A. J., Barranco, L., Cabrera, S., Castillo, F. L., ... & Estrada, O. (2019). Search for top-quark decays t→ Hq with 36 fb− 1 of pp collision data at√ s= 13 TeV with the ATLAS detector. http://hdl.handle.net/10481/60020 10.1007/JHEP05(2019)123 eng http://creativecommons.org/licenses/by/3.0/es/ info:eu-repo/semantics/openAccess Atribución 3.0 España Springer Nature