Search for single vector-like quark production in opposite-sign dilepton final states in proton-proton collisions at √s=13 TeV

A bstract A search is presented for single production of a vector-like top quark T, decaying into the standard model top quark and Higgs boson, in a final state including two opposite-sign leptons (electrons or muons), jets, and missing transverse momentum. The data were recorded by the CMS experiment in proton-proton collisions at a center-of-mass energy of 13 TeV at the CERN LHC in the years 2016–2018, and corresponding to an integrated luminosity of up to 138 fb − 1 . No excess in data over the background expectations is observed. Upper limits at 95% confidence level on the product of the T production cross section and its decay branching fraction to tH are set. The observed limits are 2.0 pb at a T mass M T = 600 GeV and 0.3 pb at M T = 1200 GeV, with a minimum of 0.1 pb at M T = 1000 GeV. This is the first search for single vector-like T quark production, followed by a decay to a top quark and the Higgs boson, in opposite-sign dilepton final states.