Search for a vector-like quark T? ? tH via the diphoton decay mode of the Higgs boson in proton-proton collisions at ?s = 13 TeV

Abstract

A search for the electroweak production of a vector-like quark T?, decaying to a top quark and a Higgs boson is presented. The search is based on a sample of proton-proton collision events recorded at the LHC at s = 13 TeV, corresponding to an integrated luminosity of 138 fb1. This is the first T? search that exploits the Higgs boson decay to a pair of photons. For narrow isospin singlet T? states with masses up to 1.1 TeV, the excellent diphoton invariant mass resolution of 1�2% results in an increased sensitivity compared to previous searches based on the same production mechanism. The electroweak production of a T? quark with mass up to 960 GeV is excluded at 95% confidence level, assuming a coupling strength ?T = 0.25 and a relative decay width ?/MT? < 5%. [Figure not available: see fulltext.]. � 2023, The Author(s).