Constraints from electric dipole moments on chargino baryogenesis in the minimal supersymmetric standard model

A commonly accepted mechanism of generating baryon asymmetry in the minimal supersymmetric standard model ~MSSM! depends on the CP violating relative phase between the gaugino mass and the Higgsino m term. The direct constraint on this phase comes from the limit of electric dipole moments ~EDM’s! of various light fermions. To avoid such a constraint, a scheme which assumes that the first two generation sfermions are very heavy is usually evoked to suppress the one-loop EDM contributions. We point out that under such a scheme the most severe constraint may come from a new contribution to the electric dipole moment of the electron, the neutron, or atoms via the chargino sector at the two-loop level. As a result, the allowed parameter space for baryogenesis in the MSSM is severely constrained, independent of the masses of the first two generation sfermions.