Search for a vector-like quark T′ → tH via the diphoton decay mode of the Higgs boson in proton-proton collisions at $$ \sqrt{s} $$ = 13 TeV
A. Tumasyan (Yerevan Physics Institute, Yerevan, Armenia, Yerevan State University, Yerevan, Armenia); W. Adam (Institut für Hochenergiephysik, Vienna, Austria); J. Andrejkovic (Institut für Hochenergiephysik, Vienna, Austria); T. Bergauer (Institut für Hochenergiephysik, Vienna, Austria); S. Chatterjee (Institut für Hochenergiephysik, Vienna, Austria); et al - Show all 2352 authors
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 $$ \sqrt{s} $$ = 13 TeV, corresponding to an integrated luminosity of 138 fb −1. 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 κ T = 0.25 and a relative decay width Γ/M T′ < 5%.