Search for the Standard Model Higgs boson produced in association with top quarks and decaying into b\bar{b} in pp collisions at √s = 13 TeV with the ATLAS detector

A search for Standard Model Higgs bosons produced in association with top-quark pairs, t\bar{t}H, is presented. The analysis uses 13.2^{−1} of pp collision data at √s = 13 TeV, collected with the ATLAS detector at the Large Hadron Collider in 2015 and 2016. The search is designed for the H→b\bar{b} decay mode and uses events with at least one top quark decaying to an electron or muon. Events are categorised according to the jet multiplicity and the number of jets containing a b-hadron decay, and multivariate techniques are used to discriminate between signal and background events, the latter being dominated by t\bar{t}+jets production. The data are consistent with either the background-only hypothesis or with the Standard Model ttH prediction. The ratio of the measured ttH signal cross-section to the Standard Model expectation is found to be μ=2.1^{+1.0}_{−0.9}, assuming a Higgs boson mass of 125 GeV.