%0 Journal Article %T Observation of Higgs boson production in association with a top quark pair at the LHC with the ATLAS detector %A ATLAS Collaboration (Aaboud, M. et al %A Alvarez Piqueras, D. %A Bailey, A. J. %A Barranco Navarro, L. %A Cabrera Urban, S. %A Castillo, F. L. %A Castillo Gimenez, V. %A Cerda Alberich, L. %A Costa, M. J. %A Escobar, C. %A Estrada Pastor, O. %A Ferrer, A. %A Fiorini, L. %A Fullana Torregrosa, E. %A Fuster, J. %A Garcia, C. %A Garcia Navarro, J. E. %A Gonzalez de la Hoz, S. %A Higon-Rodriguez, E. %A Jimenez Pena, J. %A Lacasta, C. %A Lozano Bahilo, J. J. %A Madaffari, D. %A Mamuzic, J. %A Marti-Garcia, S. %A Melini, D. %A Miñano, M. %A Mitsou, V. A. %A Rodriguez Bosca, S. %A Rodriguez Rodriguez, D. %A Ruiz-Martinez, A. %A Salt, J. %A Santra, A. %A Soldevila, U. %A Sanchez, J. %A Valero, A. %A Valls Ferrer, J. A. %A Vos, M. %J Physics Letters B %D 2018 %V 784 %I Elsevier Science Bv %@ 0370-2693 %G English %F ATLASCollaborationAaboud_etal2018 %O WOS:000445781600029 %O exported from refbase (https://references.ific.uv.es/refbase/show.php?record=3746), last updated on Sat, 13 Oct 2018 18:51:20 +0000 %X The observation of Higgs boson production in association with a top quark pair (t (t) over barH), based on the analysis of proton-proton collision data at a centre-of-mass energy of 13 TeV recorded with the ATLAS detector at the Large Hadron Collider, is presented. Using data corresponding to integrated luminosities of up to 79.8 fb(-1), and considering Higgs boson decays into b (b) over bar, WW*, tau(+)tau(-), gamma gamma, and ZZ*, the observed significance is 5.8 standard deviations, compared to an expectation of 4.9 standard deviations. Combined with the t (t) over barH searches using a dataset corresponding to integrated luminosities of 4.5 fb(-1) at 7 TeV and 20.3 fb(-1) at 8 TeV, the observed (expected) significance is 6.3 (5.1) standard deviations. Assuming Standard Model branching fractions, the total t (t) over barH production cross section at 13 TeV is measured to be 670 +/- 90(stat.)(-100)(+110)(syst.) fb, in agreement with the Standard Model prediction. %R 10.1016/j.physletb.2018.07.035 %U http://arxiv.org/abs/1806.00425 %U https://doi.org/10.1016/j.physletb.2018.07.035 %P 173-191