On String Tunneling in Power Law Inflationary Universes

Abstract

We consider the evolution of circular string loops in power law expanding universes represented by a spatially flat Friedman-Robertson-Walker metric with scale factor $a(t)\propto t^p$ where $t$ is the cosmic time and $p\ge 0$. Our main result is the existence of a "magic" power $p_m=3+2\sqrt{2}$. In spacetimes with $p<p_m$ a circular string expands either forever or to a maximal radius and then contracts until it collapses into a point (black hole). For $p>p_m$, however, we find additional types of solutions. They include configurations which contract from a positive initial radius to a minimal one and then expand forever. Their existence we interpret as an indication for the presence of a finite potential barrier. Equivalently the new solutions signal string nucleation and tunneling, phenomena recently shown to occur in de Sitter space.

Latex, 9 pages + 4 figures (not included), NBI-HE-93-50

References in corpus (1)

• Black Holes from Nucleating Strings

Cited by in corpus (4)

• Strings Propagating in the 2+1 Dimensional Black Hole Anti de Sitter Spacetime
• Circular String-Instabilities in Curved Spacetime
• Stable and Unstable Circular Strings in Inflationary Universes
• Cosmic String Nucleation near the Inflationary Phase Boundary