Origin of matter in the universe

We extend the Standard Model with two iso-singlet color triplet scalars, one singlet real scalar and one singlet fermion. The new fields are odd under an unbroken Z(2) discrete symmetry while the Standard Model particles are even. The decays of the singlet real scalar into three Standard Model quarks (antiquarks) with three singlet antifermions (fermions), which explicitly violate the baryon number, will become effective after the electroweak phase transition and then produce the observed baryon asymmetry in the universe through the loop diagram involving the exchange of the W gauge boson. The singlet fermion can serve as the candidate for cold dark matter. In our model, all new particles with masses below the TeV scale can be detected by the forthcoming collider experiments or the next generation experiments for neutron-antineutron oscillations. (C) 2007 Elsevier B.V. All rights reserved.