\midheading{$Zt$ and $Z\bar{t}$ production, processes 560--569}\

\label{subsec:Zt}
These processes describe the production of a single top quark (or antiquark) by $W$ exchange in the
$t$-channel, in association with a $Z$ boson. Processes {\tt 560}, {\tt 561},
{\tt 564}, {\tt 567} can be performed at NLO.
Processes {\tt  560}-{\tt 563} are for stable top quarks, whereas processes {\tt 564}-{\tt 569}
include the decay of the top quark and antiquark
in the approximation inwhich the top quark is taken to
be on shell allowing a clean separation
between production and decay.
For more details on this calculation, please see Ref.~\cite{Campbell:2013yla}.

For processes {\tt 564} and {\tt 567} the default behaviour is that the hadronic decay products
are clustered into jets using the supplied jet
algorithm parameters, but no cut is applied on the number of jets.
This behaviour can be altered by changing the value of the
variable {\tt notag} in the file {\tt src/User/setnotag.f}.