DOUBLE-FIELD INFLATION

We present an inflationary universe model which utilizes two coupled real scalar fields. The inflation field phi experiences a first-order phase transition and its potential dominates the energy density of the Universe during the inflationary epoch. This field phi is initially trapped in its metastable minimum and must tunnel through a potential barrier to reach the true vacuum. The second auxiliary field psi couples to the inflation field and serves as a catalyst to provide an abrupt end to the inflationary epoch; i. e., the psi field produces a time-dependent nucleation rate for bubbles of true phi vacuum. In this model, we find that bubbles of true vacuum can indeed percolate and we argue that thermalization of the interiors can more easily take place. The required degree of flatness (i. e., the fine-tuning) in the potential of the psi field is comparable to that of other models which invoke slowly rolling fields. Pseudo Nambu-Goldstone bosons may naturally provide the flat potential for the rolling field.