Çetin, Serkant Ali2020-11-042020-11-042018-041550-23681550-7998https://hdl.handle.net/11411/2415https://doi.org/10.1103/PhysRevD.97.072016A search for the standard model Higgs boson produced in association with a top-quark pair, t(t)overbarH, is presented. The analysis uses 36.1 fb(-1) of pp collision data at root s = 13 TeV collected with the ATLAS detector at the Large Hadron Collider in 2015 and 2016. The search targets the H -> b(b)overbar decay mode. The selected events contain either one or two electrons or muons from the top-quark decays, and are then categorized according to the number of jets and how likely these are to contain b-hadrons. Multivariate techniques are used to discriminate between signal and background events, the latter being dominated by ft + jets production. For a Higgs boson mass of 125 GeV, the ratio of the measured t(t)overbarH signal cross-section to the standard model expectation is found to be mu = 0.84(-0.61)(+0.64). A value of mu greater than 2.0 is excluded at 95% confidence level (C.L.) while the expected upper limit is mu < 1.2 in the absence of a t(t)overbarH signal.eninfo:eu-repo/semantics/openAccessPLUS PLUSSYMMETRIESPROGRAMMASSArticle2-s2.0-8504678989610.1103/PhysRevD.97.072016Q1WOS:000432959900001