Search For The Standard Model Higgs Boson Decaying Into Boverlineb Produced In Association With Top Quarks Decaying Hadronically In Pp Collisions At Sqrts

In this paper, a search for Higgs boson production in association with a pair of top quarks ($ t\overline{t} $H) is performed, where the Higgs boson decays to $ b\overline{b} $ , and both top quarks decay hadronically. The data used correspond to an integrated luminosity of 20.3 fb -1 of pp collisions at √s = 8 TeV collected with the ATLAS detector at the Large Hadron Collider. The search selects events with at least six energetic jets and uses a boosted decision tree algorithm to discriminate between signal and Standard Model background. The dominant multijet background is estimated using a dedicated data-driven technique. For a Higgs boson mass of 125 GeV, an upper limit of 6.4 (5.4) times the Standard Model cross section is observed (expected) at 95% confidence level. The best-fit value for the signal strength is [mu] = 1.6 ± 2.6 times the Standard Model expectation for mH = 125 GeV. Combining all $ t\overline{t}$H searches carried out by ATLAS at √s = 8 and 7 TeV, an observed (expected) upper limit of 3.1 (1.4) times the Standard Model expectation is obtained at 95% confidence level, with a signal strength [mu] = 1.7 ± 0.8.