Measurement of the t¯tH and tH production rates in the H→ b¯b decay channel using proton-proton collision data at Vs= 13 TeV

Abstract

An analysis of the production of a Higgs boson (H) in association with a top quark-antiquark pair (t¯tH) or a single top quark (tH) is presented. The Higgs boson decay into a bottom quark-antiquark pair (H → b¯b) 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 Vs = 13TeV in 2016-2018, which correspond to an integrated luminosity of 138 fb-1. The observed t¯tH production rate relative to the standard model expectation is 0.33 ± 0.26 = 0.33 ± 0.17(stat) ± 0.21(syst). Additionally, the t¯tH 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 t¯tH and tH production rates, and the results are combined with those obtained in other Higgs boson decay channels.