%0 Journal Article %T Search for the associated production of the Higgs boson with a top quark pair in multilepton final states with the ATLAS detector %A ATLAS Collaboration (Aad, G. et al %A Alvarez Piqueras, D. %A Cabrera Urban, S. %A Castillo Gimenez, V. %A Costa, M. J. %A Fernandez Martinez, P. %A Ferrer, A. %A Fiorini, L. %A Fuster, J. %A Garcia, C. %A Garcia Navarro, J. E. %A Gonzalez de la Hoz, S. %A Hernandez Jimenez, Y. %A Higon-Rodriguez, E. %A Irles Quiles, A. %A Jimenez Pena, J. %A Kaci, M. %A King, M. %A Lacasta, C. %A Lacuesta, V. R. %A Marti-Garcia, S. %A Mitsou, V. A. %A Moles-Valls, R. %A Oliver Garcia, E. %A Pedraza Lopez, S. %A Perez Garcia-Estañ, M. T. %A Romero Adam, E. %A Ros, E. %A Salt, J. %A Sanchez Martinez, V. %A Soldevila, U. %A Sanchez, J. %A Torro Pastor, E. %A Valero, A. %A Valladolid Gallego, E. %A Valls Ferrer, J. A. %A Vos, M. %J Physics Letters B %D 2015 %V 749 %I Elsevier Science Bv %@ 0370-2693 %G English %F ATLASCollaborationAad_etal2015 %O WOS:000361562900076 %O exported from refbase (https://references.ific.uv.es/refbase/show.php?record=2462), last updated on Thu, 10 Dec 2015 16:16:45 +0000 %X A search for the associated production of the Higgs boson with a top quark pair is performed in multilepton final states using 20.3 fb(-1) of proton-proton collision data recorded by the ATLAS experiment at root s = 8 TeVat the Large Hadron Collider. Five final states, targeting the decays H -> WW*, tau tau, and ZZ*, are examined for the presence of the Standard Model (SM) Higgs boson: two same-charge light leptons (e or mu) without a hadronically decaying tau lepton; three light leptons; two same-charge light leptons with a hadronically decaying tau lepton; four light leptons; and one light lepton and two hadronically decaying tau leptons. No significant excess of events is observed above the background expectation. The best fit for the t (t) over barH production cross section, assuming a Higgs boson mass of 125 GeV, is 2.1(-1.2)(+1.4) times the SM expectation, and the observed (expected) upper limit at the 95% confidence level is 4.7 (2.4) times the SM rate. The p-value for compatibility with the background-only hypothesis is 1.8s; the expectation in the presence of a Standard Model signal is 0.9 sigma. %R 10.1016/j.physletb.2015.07.079 %U http://arxiv.org/abs/1506.05988 %U https://doi.org/10.1016/j.physletb.2015.07.079 %P 519-541