Baryon asymmetry of the universe in standard electroweak theory

Abstract

We suggest a new scenario of the baryon asymmetry generation in the framework of standard electroweak theory which is based on the recent observation that anomalous baryon number violating processes are nonsuppressed at high temperatures. This scenario works if the ground state of gauge theories at high temperatures has nontrivial degeneracy with respect to the Chern-Simons number. We find that the correct baryon asymmetry is produced during the electroweak phase transition provided the microscopic asymmetry in B-violating processes δ ms⩾10 −21 and the mass of the Higgs boson in near M H ⋍ 10 GeV or M H ⋍ 56–60 GeV . In that case the sign of baryon asymmetry is entirely determined by the sign of CP violation in K 0 decays. If δ ms ⩽ 10 −21 in the standard model then cosmology requires the additional generation of heavy fermions or second doublet of scalars. The constraints on the Higgs boson mass remain unchanged provided fermion and scalar masses are less than M W.