Dynamics of minimal supersymmetric standard model flat directions consisting of multiple scalar fields

Although often chosen because of simplicity, a single scalar field does not provide a general parametrization of a minimal supersymmetric standard model (MSSM) flat direction. We derive a formalism for a class of gauge invariant polynomials which result in a multifield description of flat directions. In contrast to the single field case, the vanishing of the gauge currents yields an important dynamical constraint in the multifield framework. We consider in detail the example of the HuL flat direction and study the dynamical evolution during and after inflation. We highlight the differences between the single and the multifield flat directions. We show that in the multifield case the field space has an intrinsic curvature and hence unsuppressed non-minimal kinetic terms for the flat direction scalars arise. Also the phases of the individual components evolve non-trivially right after inflation, charging the components of the condensate and producing an enhanced entropy after the decay of the condensate, which is due to cross-coupling of different lepton flavours in the F term. However, the qualitative features of the single field Affleck–Dine baryogenesis, such as the produced total charge, remain largely unchanged.