Search for the Standard Model Higgs boson produced in association with top quarks in pp collisions at √s=8 TeV with the ATLAS detector

A search for the Standard Model Higgs boson produced in association with a pair of top quarks, t\overline{t}H, is presented. The analysis uses 20.3 fb^{-1} of pp collision data at \sqrt{s} = 8 TeV, collected with the ATLAS detector at the Large Hadron Collider during 2012. The search is designed for the H\to~b\overline{b} decay mode and uses events containing one or two leptons (electrons or/and muons). The Higgs boson is assumed to have a mass of 125 GeV. In order to improve the sensitivity of the search, events are categorised according to their jet and b-tagged jet multiplicities. A multivariate technique is used to discriminate between signal and background events, which are dominated by t\overline{t}+jets production. No significant excess of events above the background expectation is found and an observed (expected) 95% confidence-level limit of 4.1 (2.6) times the Standard Model cross section is obtained.