Measurement of the $\mathrm{t\bar{t}}$H and tH production rates in the H $\to$ $\mathrm{b\bar{b}}$ decay channel using proton-proton collision data at $\sqrt{s}$ = 13 TeV

TL;DR

This paper measures the production rates of Higgs bosons in association with top quarks using 13 TeV proton-proton collision data, providing constraints on the Higgs-top coupling and setting upper limits on tH production.

Contribution

It presents the first measurement of $ ext{t}ar{ ext{t}}$H and tH production rates in the H→bar{b} decay channel at 13 TeV, including differential measurements and coupling constraints.

Findings

Measured $ ext{t}ar{ ext{t}}$H rate at 0.33 ± 0.26 times the SM expectation.

Set an upper limit of 14.6 times the SM prediction for tH production rate.

Derived constraints on the Higgs-top coupling structure.

Abstract

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