中国物理学会高能物理分会第十三届全国粒子物理学术会议（2021）

A search is presented for single production of a vector-like quark T of electric charge +2/3 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 recorded at the CERN LHC in 2016-2018, corresponding to an integrated luminosity of 136 fb−1. The search is sensitive to a T quark mass between 0.6 and 1.8 TeV with decay widths ranging from narrow up to 30% of the T quark mass. Reconstruction strategies for the top quark are optimized for boosted and non-boosted regimes. At the 95% confidence level, in the studied T quark mass range the product of the cross section and branching fraction is excluded above values in the range 15-602 fb for a T quark of narrow decay width, and above values in the range 16-836 fb for decay widths from 10% to 30% of the T quark mass.