It has been recently shown that the observed baryon number may origina
te at the electroweak phase transition, provided that the Higgs boson
and the lightest stop are sufficiently light, In this work, we perform
a detailed analysis, including all dominant two-loop finite-temperatu
re corrections to the Higgs effective potential, as well as the non-tr
ivial effects proceeding from the mixing in the stop sector, to define
the region of parameter space for which electroweak baryogenesis can
happen. The limits on the stop and Higgs masses are obtained by taking
into account the experimental bounds on these quantities, as well as
those coming from the requirement of avoiding dangerous color breaking
minima.We find for the Higgs mass m(h) less than or similar to 105 Ge
V, while the stop mass may be close to the present experimental bound
and must be smaller than, or of the order of, the top quark mass. Thes
e results provide a very strong motivation for further non-perturbativ
e analysis of the electroweak phase transition, as well as for the sea
rch for Higgs and stop particles at the LEP and Tevatron colliders. (C
) 1998 Elsevier Science B.V.