Domain wall production during inflationary reheating

We numerically investigate the decay, via parametric resonance, of the inflaton with an m(2) phi(2) potential into a scalar matter field with a symmetry breaking potential. We consider the case where symmetry breaking takes place during inflation, but where thermal symmetry restoration cannot occur during or after preheating. We show that when expansion is not taken into account during reheating, non-thermal symmetry restoration and defect production is possible. However in an expanding universe the fields do not spend sufficient time in the instability bands, thus symmetry restoration and subsequent domain wall production do not occur. [S0556-2821(99)06220-7].