TY - JOUR AU - ATLAS Collaboration (Aaboud, M. et al AU - Alvarez Piqueras, D. AU - Barranco Navarro, L. AU - Cabrera Urban, S. AU - Castillo Gimenez, V. AU - Cerda Alberich, L. AU - Costa, M. J. AU - Escobar, C. AU - Estrada Pastor, O. AU - Fernandez Martinez, P. AU - Ferrer, A. AU - Fiorini, L. AU - Fuster, J. AU - Garcia, C. AU - Garcia Navarro, J. E. AU - Gonzalez de la Hoz, S. AU - Higon-Rodriguez, E. AU - Jimenez Pena, J. AU - Lacasta, C. AU - Madaffari, D. AU - Mamuzic, J. AU - Marti-Garcia, S. AU - Melini, D. AU - Mitsou, V. A. AU - Pedraza Lopez, S. AU - Rodriguez Bosca, S. AU - Rodriguez Rodriguez, D. AU - Romero Adam, E. AU - Salt, J. AU - Soldevila, U. AU - Sanchez, J. AU - Valero, A. AU - Valls Ferrer, J. A. AU - Vos, M. PY - 2018 DA - 2018// TI - Search for flavour-changing neutral current top-quark decays t -> qZ in proton-proton collisions at root s=13 TeV with the ATLAS detector T2 - J. High Energy Phys. JO - Journal of High Energy Physics SP - 176 EP - 41pp VL - 07 IS - 7 PB - Springer KW - Hadron-Hadron scattering (experiments) AB - A search for flavour-changing neutral-current processes in top-quark decays is presented. Data collected with the ATLAS detector from proton-proton collisions at the Large Hadron Collider at a centre-of-mass energy of root s = 13TeV, corresponding to an integrated luminosity of 36.1 fb(-1), are analysed. The search is performed using top-quark pair events, with one top quark decaying through the t -> qZ (q = u, c) flavour-changing neutral-current channel, and the other through the dominant Standard Model mode t -> bW. Only Z boson decays into charged leptons and leptonic W boson decays are considered as signal. Consequently, the final-state topology is characterized by the presence of three isolated charged leptons (electrons or muons), at least two jets, one of the jets originating from a b-quark, and missing transverse momentum from the undetected neutrino. The data are consistent with Standard Model background contributions, and at 95% confidence level the search sets observed (expected) upper limits of 1.7 x 10(-4) (2.4 x 10(-4)) on the t -> uZ branching ratio and 2.4 x 10(-4) (3.2 x 10(-4)) on the t -> cZ branching ratio, constituting the most stringent limits to date. SN - 1029-8479 UR - http://arxiv.org/abs/1803.09923 UR - https://doi.org/10.1007/JHEP07(2018)176 DO - 10.1007/JHEP07(2018)176 LA - English N1 - WOS:000443814800001 ID - ATLASCollaborationAaboud_etal2018 ER -