Search for production of a single vectorlike quark decaying to 𝑡⁢𝐻 or 𝑡⁢𝑍 in the all-hadronic final state in 𝑝⁢𝑝 collisions at √𝑠 =13 TeV

Abstract

A search for electroweak production of a single vectorlike 𝑇 quark in association with a bottom (𝑏) quark in the all-hadronic decay channel is presented. This search uses proton-proton collision data at √𝑠 =13 TeV collected by the CMS experiment at the CERN LHC during 2016–2018, corresponding to an integrated luminosity of 138 fb−1. The 𝑇 quark is assumed to have charge 2/3 and decay to a top (𝑡) quark and a Higgs (𝐻) or 𝑍 boson. Hadronic decays of the 𝑡 quark and the 𝐻 or 𝑍 boson are reconstructed from the kinematic properties of jets, including those containing 𝑏 hadrons. No deviation from the standard model prediction is observed in the reconstructed 𝑡⁢𝐻 and 𝑡⁢𝑍 invariant mass distributions. The 95% confidence level upper limits on the product of the production cross section and branching fraction of a 𝑇 quark produced in association with a 𝑏 quark and decaying via 𝑡⁢𝐻 or 𝑡⁢𝑍 range from 1260 to 68 fb for 𝑇 quark masses of 600–1200 GeV.