Evading the cosmological domain wall problem

Abstract

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 vacuua is favoured 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.Comment: 17 pages (revtex), including 9 figures (epsf); Revised to include test of numerical approximation used; No change in results or conclusions; accepted for publication in Phys Rev D. PostScript available at ftp://ftp.physics.ox.ac.uk/pub/local/users/sarkar/Domainwalls.ps.g

Gravitational waves as a probe of the gravitino mass

“…The numerical [19,20,21] and analytical [22] results obtained so far show that the domain walls reach a scaling regime in simple models. We therefore assume that the evolution of the domain walls is given by the scaling law 3 .…”

“…where f 0 is given by (21). Note that the intensity of the gravitational waves is very sensitive to the dynamical scale, Λ.…”

Cosmological evolution of domain wall networks

“…In fact, in previous simulations of cosmological domain wall evolution [5,6,7,8,9] some hints for deviations to a scale-invariant evolution were found. The question we wish to address presently is whether these deviations remain if one performs larger runs.…”

“…We do find some statistical evidence for deviations to the scale-invariant behaviour, though there is some dependency on dimensionality and * Electronic address: jeolivei@fc.up.pt † Electronic address: C.J.A.P.Martins@damtp.cam.ac.uk ‡ Electronic address: ppavelin@fc.up.pt box sizes. While 2D and 3D numerical simulations have been previously carried out (though usually in smaller boxes or with smaller dynamic range) by a number of authors [5,6,7,8,9], we have also carried out for the first time a series of 4D simulations, which in a simple phenomenological way may be of interest to brane world scenarios [10,11].…”

Classical bounce: Constraints and consequences

“…Taking into account the effects caused by the evolution of the background, it seems probable, though by no means guaranteed, that the subsequent contraction would result in high decay rates of wall and antiwall configurations, possibly leading to a simple and automatic solution of the wall puzzle (with tremendous production of particles). The remaining wall distribution can, once transfered into the expanding epoch, be made consistent with observations, e.g., the CMB [39,40], provided the network is strongly frustrated [47], or if an initial bias, however tiny [48,49,50], is introduced in the potential.…”