BARYOGENESIS FROM FLAT DIRECTIONS OF THE SUPERSYMMETRIC STANDARD MODEL

Baryogenesis from the coherent production of a scalar condensate along a hat direction of the supersymmetric extension of the standard model (Affleck-Dine mechanism) is investigated. Two important effects are e mphasized First, non-renormalizable terms in the superpotential can li ft standard model flat directions at large field values. Second, the f inite energy density in the early universe induces soft potentials wit h curvature of order the Hubble constant. Both these have important im plications for baryogenesis, which requires large squark or slepton ex pectation values to develop along flat directions. In particular, the induced mass squared must be negative. The resulting baryon to entropy ratio is very insensitive to the details of the couplings and initial conditions, but depends on the dimension of the non-renormalizable op erator in the superpotential which stabilizes the flat direction and t he reheat temperature after inflation. Unlike the original scenario, a n acceptable baryon asymmetry can result without subsequent entropy re leases. In the simplest scenario the baryon asymmetry is generated alo ng the LH(u) flat direction, and is related to the mass of the lightes t neutrino.