  In the context of simplified models of dark matter, the contributions of a
scalar mediator to top quark production processes are considered. Tree-level
and one-loop contributions of the mediator's decay into a top-antitop quark
pair in two-, three-, and four-top quarks production processes are calculated.
A significant contribution from diagrams involving the dark matter mediator is
demonstrated in the total cross section for three- and four-top quark
production processes, taking into account current experimental limits on model
parameters. The perspective of searching for dark matter mediators in the
processes under consideration is determined by the ability to reconstruct the
final state with modern collider detectors and the experimental sensitivity
that has already been achieved for such rare events.
