BIASED DOMAIN-WALLS

Domain walls form naturally in the early Universe whenever a discrete symmetry is spontaneously broken at some phase transition. When each v acuum is populated equally, it is well known that the domain wall netw ork comes to dominate the energy density of the Universe and causes ex cessive anisotropy in the cosmic microwave background. We present resu lts for the initial conditions and dynamical evolution of domain wall networks in which one of the degenerate vacua has a population bias ov er the other. The initial distribution of domain walls is well describ ed by percolation theory. We find that such networks, although they sh ow evidence of a limited scaling regime for a range of biases, do not persist indefinitely. It follows that biased domain wall networks avoi d the energy density and anisotropy problems.