ATLAS collaboration (2935 authors)Aguilar Saavedra, Juan AntonioAmor Dos Santos, Susana PatriciaAraque Espinosa, Juan PedroCastro, Nuno FilipeConde Muino, PatriciaDa Cunha Sargedas De Sousa, Mario JoseDias DO Vale, TiagoFaisca Rodrigues Pereira, Rui MiguelFiolhais, MiguelGalhardo, BrunoGomes, AgostinhoGoncalo, RicardoJorge, PedroMachado Miguens, JoanaMaio, AmeliaManeira, JoseMendes Gouveia, Emanuel DemetrioOleiro Seabra, Luis FilipeOnofre, AntonioCosta Batalha Pedro, RutePereira Peixoto, Ana PaulaSantos, HelenaSaraiva, JoaoSilva, Jose ManuelTavares Delgado, AdemarVeloso, FilipeWolters, Helmut2019-02-052019-02-052018-11-10http://dx.doi.org/10.1016/j.physletb.2018.09.013http://hdl.handle.net/10400.26/27716A search for the decay of the Standard Model Higgs boson into a bb¯ pair when produced in association with a W or Z boson is performed with the ATLAS detector. The data, corresponding to an integrated luminosity of 79.8fb−1 were collected in proton–proton collisions during Run 2 of the Large Hadron Collider at a centre-of-mass energy of 13TeV . For a Higgs boson mass of 125GeV , an excess of events over the expected background from other Standard Model processes is found with an observed (expected) significance of 4.9 (4.3) standard deviations. A combination with the results from other searches in Run 1 and in Run 2 for the Higgs boson in the bb¯ decay mode is performed, which yields an observed (expected) significance of 5.4 (5.5) standard deviations, thus providing direct observation of the Higgs boson decay into b -quarks. The ratio of the measured event yield for a Higgs boson decaying into bb¯ to the Standard Model expectation is 1.01±0.12(stat.)−0.15+0.16(syst.) . Additionally, a combination of Run 2 results searching for the Higgs boson produced in association with a vector boson yields an observed (expected) significance of 5.3 (4.8) standard deviations.engjournal article2019-02-05