UV Finite Brane Decay

TL;DR

This paper analyzes the decay of unstable D-branes in subcritical string theory with a spacelike linear dilaton, providing exact calculations of decay rates and showing the absence of UV divergences present in critical string theory.

Contribution

It offers an exact expression for the annulus diagram in subcritical string theory and discusses implications for tachyon dust, advancing understanding of brane decay in non-critical backgrounds.

Findings

UV divergences are absent for nonzero spacelike dilaton.

Exact annulus diagram expression derived with natural incoming vacua.

Implications for tachyon dust discussed.

Abstract

The decay of an unstable D-brane via closed string emission and open string pair production is considered in subcritical string theory with a spacelike linear dilaton. The decay rate is given by the imaginary part of the annulus, which has ambiguities corresponding to the choices of incoming closed and open string vacua. An exact expression for the full annulus diagram is computed with a natural choice of incoming vacua. It is found that the ultraviolet divergences present in critical string theory in both of these processes are absent for any nonzero spacelike dilaton. Implications for the vexing issue of the tachyon dust are discussed.