  A search for single production of vector-like top quark partners (T) decaying
into a Higgs boson and a top quark is performed using data from pp collisions
at a centre-of-mass energy of 13 TeV collected by the CMS experiment at the
CERN LHC, corresponding to an integrated luminosity of 2.3 inverse femtobarns.
The top quark decay includes an electron or a muon while the Higgs boson decays
into a pair of b quarks. No significant excess over standard model backgrounds
is observed. Exclusion limits on the product of the production cross section
and the branching fraction are derived in the T quark mass range 700 to 1800
GeV. For a mass of 1000 GeV, values of the product of the production cross
section and the branching fraction greater than 0.8 and 0.7 pb are excluded at
95% confidence level, assuming left- and right-handed coupling of the T quark
to standard model particles, respectively. This is the first analysis setting
exclusion limits on the cross section of singly produced vector-like T quarks
at a centre-of-mass energy of 13 TeV.
