Searches are performed for resonances decaying to two jets, with at least one jet originating from a b quark, in proton-proton collisions at $\sqrt{s}=13$ TeV. The dataset corresponds to an integrated luminosity of 137 fb$^{-1}$ collected by the CMS detector at the LHC. Jets are identified as containing energetic b hadrons using a deep neural network b tagger. The invariant mass spectrum of b-tagged dijets is well described by a smooth parameterization and no evidence for the production of new particles is observed. Cross-section upper limits are set on resonances decaying into b quarks. These limits exclude at $95\%$ confidence level models of Z' bosons with a mass less than 2.4 TeV, and an excited b quark with mass less than 4.0 TeV.
Signal shapes of b* from the process bg$\rightarrow$b∗$\rightarrow$bg. Shown are the wide jets used to reconstruct the dijet mass spectra.
The acceptance times efficiency of the event selection for a Z'$\rightarrow$bb resonance as a function of the resonance mass.
The differential cross sections as a function of the dijet mass for the double b tagging category during 2016.
A search for single production of a vector-like T quark with charge $2/3\,e$, in the decay channel with a top quark and a neutral scalar boson $\phi$ is presented. The $\phi$ boson can be a standard model Higgs boson or a new particle beyond the standard model. The top quark is identified in its leptonic decay, and the neutral boson decays into a bottom quark-antiquark pair. Final states with boosted topologies are considered and machine learning techniques are exploited for optimal classification. The analysis uses data collected by the CMS experiment in proton-proton collisions at a center-of-mass energy of $13~\mathrm{TeV}$, corresponding to an integrated luminosity of $138~\mathrm{fb}^{-1}$ recorded at the CERN LHC in 2016$-$2018. Limits at $95\%$ confidence levels are set on the product of the cross section and branching fraction for a T quark of small decay width. They are in the range between 15 and $0.15~\mathrm{fb}$, depending on T quark and $\phi$ boson masses. In the case of the decay channel with a top quark and a standard model Higgs boson, for most of the studied range the analysis provides limits which are better or comparable with previous searches performed in CMS.
Distribution of the mass of the AK8 jet selected as the $\phi$ boson candidate for data and simulated background events in the (TopT, XbbL) validation region for the muon channel. The distribution is shown before the final fit for signal extraction.
Distribution of the mass of the AK8 jet selected as the $\phi$ boson candidate for data and simulated background events in the (TopT, XbbL) validation region for the electron channel. The distribution is shown before the final fit for signal extraction.
Distribution of the mass of the AK8 jet selected as the $\phi$ boson candidate for data and simulated background events in the (TopL, XbbL) validation region for the muon channel. The distribution is shown before the final fit for signal extraction.
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