$\mathrm{t\bar{t}H/tH}$ production at CMS

TL;DR

This paper reports CMS measurements of $ ext{t}ar{ ext{t}} ext{H}$ and $ ext{tH}$ production at 13 TeV, confirming SM predictions and observing $ ext{t}ar{ ext{t}} ext{H}$ in a new decay channel, probing the Higgs-top coupling.

Contribution

First observation of $ ext{t}ar{ ext{t}} ext{H}$ in a single Higgs decay channel and tests of its CP structure using CMS data at 13 TeV.

Findings

Results are consistent with Standard Model predictions.

First observation of $ ext{t}ar{ ext{t}} ext{H}$ in a single decay channel.

Initial tests of the CP structure of the Higgs-top coupling.

Abstract

After the Higgs boson discovery, a main focus at the CERN LHC has been the measurement of its properties. Observing the Higgs boson associated production with a top quark-antiquark pair ($\mathrm{t\bar{t}H}$) is particularly interesting because it provides tree-level access to measuring the Higgs boson-top quark Yukawa coupling. However, the production of a single top quark in association with the Higgs boson ($\mathrm{tH}$) is also sensitive to the sign of this coupling. This coupling is essential for the stability of the Higgs potential at high energy scales and can also be a probe for physics beyond the standard model (SM). The latest measurements of the $\mathrm{t\bar{t}H}$ and $\mathrm{tH}$ associated production rates performed by the CMS Collaboration with proton-proton collision events at $\sqrt{s} =13$ TeV in the diphoton and multilepton channels are presented here. Events are categorized according to the lepton and jet multiplicities, and multivariate classifiers are used to distinguish signal from background processes. The results are consistent with the SM predictions and feature the first observation of $\mathrm{t\bar{t}H}$ production in a single Higgs boson decay channel along with the first tests of its CP structure.