@Article{ATLASCollaborationAaboud_etal2019, author="ATLAS Collaboration (Aaboud, M. et al and Alvarez Piqueras, D. and Aparisi Pozo, J. A. and Bailey, A. J. and Barranco Navarro, L. and Cabrera Urban, S. and Castillo, F. L. and Castillo Gimenez, V. and Cerda Alberich, L. and Costa, M. J. and Escobar, C. and Estrada Pastor, O. and Ferrer, A. and Fiorini, L. and Fullana Torregrosa, E. and Fuster, J. and Garcia, C. and Garcia Navarro, J. E. and Gonzalez de la Hoz, S. and Higon-Rodriguez, E. and Jimenez Pena, J. and Lacasta, C. and Lozano Bahilo, J. J. and Madaffari, D. and Mamuzic, J. and Marti-Garcia, S. and Melini, D. and Mi{\~{n}}ano, M. and Mitsou, V. A. and Rodriguez Bosca, S. and Rodriguez Rodriguez, D. and Ruiz-Martinez, A. and Salt, J. and Santra, A. and Soldevila, U. and Sanchez, J. and Valero, A. and Valls Ferrer, J. A. and Vos, M.", title="Search for top-quark decays t -> Hq with 36 fb(-1) of pp collision data at root s=13 TeV with the ATLAS detector", journal="Journal of High Energy Physics", year="2019", publisher="Springer", volume="05", number="5", pages="123--67pp", optkeywords="Hadron-Hadron scattering (experiments); Rare decay; Top physics", abstract="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 = 13 TeV recorded in 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider and corresponding to an integrated luminosity of 36.1 fb(-1). Two complementary analyses are performed to 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 Hbb and H (+-) decay modes, respectively. The high multiplicity of b-quark jets, or the presence of hadronically decaying -leptons, is 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 x 10(-3) (8.3 x 10(-4)) and 1.2 x 10(-3) (8.3 x 10(-4)), respectively. The corresponding combined observed (expected) upper limits on the |(tcH)| and |(tuH)| couplings are 0.064 (0.055) and 0.066 (0.055), respectively.", optnote="WOS:000468948900001", optnote="exported from refbase (https://references.ific.uv.es/refbase/show.php?record=4033), last updated on Wed, 12 Jun 2019 15:56:45 +0000", issn="1029-8479", doi="10.1007/JHEP05(2019)123", opturl="https://arxiv.org/abs/1812.11568", opturl="https://doi.org/10.1007/JHEP05(2019)123", language="English" }