An analysis of the production of a Higgs boson (H) in association with a top quark-antiquark pair (tt¯H) or a single top quark (tH) is presented. The Higgs boson decay into a bottom quark-antiquark pair (H → bb¯) is targeted, and three different final states of the top quark decays are considered, defined by the number of leptons (electrons or muons) in the event. The analysis utilises proton-proton collision data collected at the CERN LHC with the CMS experiment at s√ = 13 TeV in 2016-2018, which correspond to an integrated luminosity of 138 fb−1. The observed tt¯H production rate relative to the standard model expectation is 0.33 ± 0.26 = 0.33 ± 0.17 (stat) ± 0.21 (syst). Additionally, the tt¯H production rate is determined in intervals of Higgs boson transverse momentum. An upper limit at 95% confidence level is set on the tH production rate of 14.6 times the standard model prediction, with an expectation of 19.3 +9.2−6.0. Finally, constraints are derived on the strength and structure of the coupling between the Higgs boson and the top quark from simultaneous extraction of the tt¯H and tH production rates, and the results are combined with those obtained in other Higgs boson decay channels.
