Search for single productio no vector-like quarks decaying to a Z boson and a top or a bottom quark in proton-proton collisions at root s=13 TeV

Abstract

A search for single production of vector-like quarks, T and B, decaying into a Z boson and a top or a bottom quark, respectively, is presented. The search is performed using data collected by the CMS experiment at the LHC in proton-proton collisions at root s = 13TeV, corresponding to an integrated luminosity of 2.3 fb(-1). An exotic T quark production mode through the decay of a heavy Z resonance is also considered. The search is performed in events with a Z boson decaying leptonically, accompanied by a bottom or a top quark decaying hadronically. No excess of events is observed over the standard model background expectation. Products of production cross section and branching fraction for T and B quarks from 1.26 and 0.13 pb are excluded at 95% confidence level for the range of resonance mass considered, which is between 0.7 and 1.7TeV. Limits on the product of the Z 0 boson production cross section and branching fraction, with the Z boson decaying to the Tt final state, are set between 0.31 and 0.13 pb, for Z boson masses in the range from 1.5 to 2.5 TeV. This is the first search at 13TeV for single production of vector-like quarks in events with a Z boson decaying leptonically accompanied by boosted jets.