A search for flavor-changing neutral current interactions of the top quark (t) and the Higgs boson (H) is presented. The search is based on a data sample corresponding to an integrated luminosity of 137 fb$^{-1}$ recorded by the CMS experiment at the LHC in proton-proton collisions at $\sqrt{s}$ = 13 TeV. Events containing exactly one lepton (muon or electron) and at least three jets, among which at least two are identified as originating from the hadronization of a bottom quark, are analyzed. A set of deep neural networks is used for kinematic event reconstruction, while boosted decision trees 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 extracted. These limits are interpreted in terms of top quark decay branching fractions ($\mathcal{B}$) to the Higgs boson and an up (u) or a charm quark (c). Assuming one nonvanishing extra coupling at a time, the observed (expected) upper limits at 95% confidence level are $\mathcal{B}$(t $\to$ Hu) $\lt$ 0.079 (0.11)% and $\mathcal{B}$(t $\to$ Hc) $\lt$ 0.094 (0.086)%.
Number of events in the combined 2017+2018 data and simulated backgrounds, shown separately for each jet category, with uncertainties obtained from the fit, assuming a nonzero Hct coupling.
The observed (expected) $95\%$ CL exclusion limits on the branching fractions $\mathcal{B}(\mathrm{t}\to\mathrm{Hu})$ and $\mathcal{B}(\mathrm{t}\to\mathrm{Hc})$.
The observed (expected) $95\%$ CL exclusion limits on the anomalous couplings $\kappa_{\mathrm{Hut}}$ and $\kappa_{\mathrm{Hct}}$.
A search is presented for new particles produced in proton-proton collisions at $\sqrt{s}=13~\mathrm{TeV}$ at the LHC, using events with energetic jets and large missing transverse momentum. The analysis is based on a data sample corresponding to an integrated luminosity of $101~\mathrm{fb}^{-1}$, collected in 2017$-$2018 with the CMS detector. Separate categories are defined for events with narrow jets from initial-state radiation and with large-radius jets consistent with a hadronic decay of a W or a Z boson. Novel machine learning techniques are used to identify hadronic W and Z boson decays. The analysis is combined with an earlier search based on a data sample corresponding to an integrated luminosity of $36~\mathrm{fb}^{-1}$, collected in 2016. No significant excess of events is observed with respect to the standard model background expectation, as determined from control samples in data. The results are interpreted in terms of limits on the branching fraction of an invisible decay of the Higgs boson, as well as constraints on simplified models of dark matter, on first-generation scalar leptoquarks decaying to quarks and neutrinos, and on gravitons in models with large extra dimensions. Several of the new limits are the most restrictive to date.
Differential signal yields for various signal hypotheses.
Differential signal yields for various signal hypotheses.
Differential signal yields for various signal hypotheses.