  We present two minimal extensions of the standard model, each giving rise to
baryogenesis. They include heavy color-triplet scalars interacting with a light
Majorana fermion that can be the dark matter (DM) candidate. The electroweak
charges of the new scalars govern their couplings to quarks of different
chirality, which leads to different collider signals. These models predict
monotop events at the LHC and the energy spectrum of decay products of highly
polarized top quarks can be used to establish the chiral nature of the
interactions involving the heavy scalars and the DM. Detailed simulation of
signal and standard model background events is performed, showing that top
quark chirality can be distinguished in hadronic and leptonic decays of the top
quarks.
