Semiclassical decay of near extremal fivebranes

TL;DR

This paper studies the semiclassical decay process of near-extremal fivebranes in string theory, revealing how energy leaks via Hawking radiation and the throat geometry influences the decay dynamics.

Contribution

It demonstrates that near-extremal fivebranes can be analyzed using semiclassical string theory under certain conditions and connects the decay process to the CGHS model with massive fields.

Findings

Energy leaks as Hawking radiation at a rate of 1/k^{7/2}

Throat becomes infinitely long as g approaches zero

Radiation persists but does not reach infinity in the g→0 limit

Abstract

We argue that a near-extremal charge-$k$ type II NS fivebrane can be reliably described in semiclassical string perturbation theory as long as both $k$ and $\mu \over k$ are large, where $\mu$ is the energy density in string units. For a small value of the asymptotic string coupling $g$, the dynamics in the throat surrounding the fivebrane reduces to the CGHS model with massive fields. We find that the energy density leaks off the brane in the form of Hawking radiation at a rate of order $1 \over k^{7/2}$ in string units independently of $g$ to leading order. In the $g\to 0$ limit the radiation persists but never reaches asymptotic infinity because the throat becomes infinitely long.