Search for production of single vector-like quarks decaying to tH or tZ in the all-hadronic final state in pp collisions at sqrt(s) = 13 TeV

A search for electroweak production of a single vector-like quark $\mathrm{T}$ in association with a bottom quark ($\mathrm{b}$) and decaying fully hadronically is presented. This search uses proton-proton collision data at $\sqrt{s} = 13~\mathrm{TeV}$ collected by the CMS experiment at the CERN LHC during 2016--2018, corresponding to an integrated luminosity of $138~\mathrm{fb}^{-1}$. The $\mathrm{T}$ can have charge $2/3$ and can decay to a top quark ($\mathrm{t}$) and a Higgs or $\mathrm{Z}$ boson. Event kinematics and the presence of jets containing $\mathrm{b}$ hadrons are used to reconstruct the hadronic decays of the $\mathrm{t}$ and Higgs or $\mathrm{Z}$ boson. No discrepancy from the standard model prediction is observed in the data. For $\mathrm{T}$ masses from $600$ to $1200~\mathrm{GeV}$, the $95\%$ confidence level upper limits on the production cross section of a $\mathrm{T}$ produced in association with a $\mathrm{b}$ and decaying via a $\mathrm{t}$ and a Higgs or $\mathrm{Z}$ boson range from $1260$ to $68~\mathrm{fb}$.