Dark matter in $R+R^2$ cosmology
  Production of massive stable relics in $R^2$-modified gravity is considered.
It is shown that the cosmological evolution and kinetics of massive species
differs significantly from those in the conventional cosmology. The results are
applied to the lightest supersymmetric particles and it is argued that they are
viable candidates for the constituents of dark matter, if their mass is about
1000 TeV.
