Search for flavor-changing neutral current interactions of the top quark and the Higgs boson decaying to a bottom quark-antiquark pair at $\sqrt{s}=13~\mathrm{TeV}$

A search for flavor-changing neutral current interactions between the top quark and the Higgs boson is presented. The search is based on a data sample corresponding to an integrated luminosity of $137~\mathrm{fb}^{-1}$ recorded by the CMS experiment at the LHC in proton-proton collisions at $\sqrt{s}=13~\mathrm{TeV}$. Events containing exactly one lepton (electron or muon) and at least three jets, among which at least two are identified as coming from the hadronization of a b quark, are analyzed. Selected events are separated into five categories based on the jet and b jet multiplicity. A deep neural network is used to associate the reconstructed objects to the matrix-element partonic final state, while boosted decision trees are used to distinguish the signal from the background events. No significant excess over the background predictions is observed, and upper limits on the signal production cross sections are set. These limits are interpreted in terms of top quark decay branching fractions. Assuming one nonvanishing extra coupling at a time, the observed (expected) upper limits at the $95\%$ confidence level are $\mathcal{B}(\mathrm{t}\to\mathrm{Hu}) < 7.9 \times 10^{-4}~(1.1 \times 10^{-3})$ and $\mathcal{B}(\mathrm{t}\to\mathrm{Hc}) < 9.4 \times 10^{-4}~(8.6 \times 10^{-4})$.