  We study fermionic atoms of three different internal quantum states (colors)
in an optical lattice, which are interacting through attractive on site
interactions, U<0. Using a variational calculation for equal color densities
and small couplings, |U| < |U_C|, a color superfluid state emerges with a
tendency to domain formation. For |U| > |U_C|, triplets of atoms with different
colors form singlet fermions (trions). These phases are the analogies of the
color superconducting and baryonic phases in QCD. In ultracold fermions, this
transition is found to be of second order. Our results demonstrate that quantum
simulations with ultracold gases may shed light on outstanding problems in
quantum field theory.
