Search for single production of a vector-like T quark decaying to a top quark and a Z boson in the final state with jets and missing transverse momentum at $\sqrt{s}$ = 13 TeV

The collaboration
CMS-B2G-19-004, 2022.

Abstract (data abstract)
A search is presented for single production of a vector-like T quark with charge $2e/3$, in the decay channel featuring a top quark and a Z boson, with the top quark decaying hadronically and the Z boson decaying to neutrinos. The search uses data collected by the CMS experiment in proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 136 $\mathrm{fb}^{-1}$ recorded at the CERN LHC in 2016--2018. The search is sensitive to a T quark mass between 0.6 and 1.8 TeV with decay widths ranging from negligibly small up to 30$\%$ of the T quark mass. Reconstruction strategies for the top quark are based on the degree of Lorentz boosting of its final state. At 95$\%$ confidence level, the upper limit on the product of the cross section and branching fraction for a T quark of small decay width varies between 15 and 602 $\mathrm{fb}$, depending on its mass. For a T quark with decay widths between 10 and 30$\%$ of its mass, this upper limit ranges between 16 and 836 $\mathrm{fb}$. For most of the studied range, the results provide the best limits to date. This is the first search for single T quark production based on the full Run 2 data set of the LHC.