Search for $\mathrm{t\overline{t}H}$ production in the $\mathrm{H}\rightarrow \mathrm{b\overline{b}}$ decay channel with 2016 pp collision data at $\sqrt{s}=13~\mathrm{TeV}$

The results of the search for the associated production of a Higgs boson with a top quark-antiquark pair ($\mathrm{t\overline{t}H}$) in proton-proton collisions at a center-of-mass energy of $\sqrt{s} = 13\,$TeV are presented. The data correspond to an integrated luminosity of up to $12.9~\mathrm{fb}^{-1}$ recorded with the CMS experiment in 2016. Candidate $\mathrm{t\overline{t}H}$ events are selected with criteria enhancing the lepton+jets or dilepton decay-channels of the $\mathrm{t\overline{t}}$ system and the decay of the Higgs boson into a bottom quark-antiquark pair ($\mathrm{H}\rightarrow \mathrm{b\overline{b}}$). In order to increase the sensitivity of the search, selected events are split into several categories with different expected signal and background rates. In each category signal and background events are separated using a multivariate approach that combines a matrix element method with boosted decision trees. The results are characterized by an observed $\mathrm{t\overline{t}H}$ signal strength relative to the standard model cross section, $\mu = \sigma/\sigma_{{\rm SM}}$, under the assumption of $m_{H} = 125\,$GeV. A combined fit of multivariate discriminant distributions in all categories results in an observed (expected) upper limit of $\mu < 1.5~(1.7)$ at the $95\%$ confidence level, and a best fit value of $\mu = -0.19\,^{+0.45}_{-0.44}(\text{stat.})\,^{+0.66}_{-0.68}(\text{syst.})$.