2 Search Results

Abstract not provided.

The observation of Higgs boson production in association with a top quark pair ($$t\bar{t}H$$), based on the analysis of proton-proton collision data at a centre-of-mass energy of 13 TeV recorded with the ATLAS detector at the Large Hadron Collider, is presented. Using data corresponding to integrated luminosities of up to 79.8 fb^-1, and considering Higgs boson decays into $$b\bar{b}$$, WW^*, τ⁺τ^-, γγ, and ZZ^*, the observed significance is 5.8 standard deviations, compared to an expectation of 4.9 standard deviations. Combined with the $$t\bar{t}H$$ searches using a dataset corresponding to integrated luminosities of 4.5 fb^-1 at 7 TeV and 20.3 fb^-1 at 8 TeV, the observed (expected) significance is 6.3 (5.1) standard deviations. Assuming Standard Model branching fractions, the total $$t\bar{t}H$$ production cross section at 13 TeV is measured to be 670 ± 90 (stat.)$$^{+110}_{-100}$$ (syst.) fb, in agreement with the Standard Model prediction.