Peter L. White | Searcharxiv

arXiv1997

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 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.

hep-ph↗

arXiv1992

The Boundary Cosmological Constant in Stable 2D Quantum Gravity

We study further the rôle of the boundary operator $Ø_B$ for macroscopic loop length in the stable definition of 2D quantum gravity provided by the $[{\tilde P},Q]=Q$ formulation. The KdV flows are supplemented by an additional flow with respect to the boundary cosmological constant $σ$. We numerically study these flows for the $m=1$, $2$ and $3$ models, solving for the string susceptibility in the presence of $Ø_B$ for arbitrary coupling $σ$. The spectrum of the Hamiltonian of the loop quantum mechanics is continuous and bounded from below by $σ$. For large positive $σ$, the theory is dominated by the `universal' $m=0$ topological phase present only in the $[{\tilde P},Q]=Q$ formulation. For large negative $σ$, the non--perturbative physics approaches that of the $[P,Q]=1$ definition, although there is no path to the unstable solutions of the $[P,Q]=1$ $m$-even models.

hep-th↗