Evading the cosmological domain wall problem

Discrete symmetries are commonplace in field theoretical models but pose a severe problem for cosmology since they lead to the formation of domain walls during spontaneous symmetry breaking in the early universe. However, if one of the vacua is favored over the others, either energetically or because of initial conditions, it will eventually come to dominate the universe. Using numerical methods, we study the evolution of the domain wall network for a variety of field configurations in two and three dimensions and quantify the rate at which the walls disappear. Good agreement is found with a recent analytic estimate of the termination of the scaling regime of the wall network. We conclude that there is no domain wall problem in the postinflationary universe for a weakly coupled field which is not in thermal equilibrium.