Note on Light-like Tachyon Condensation

TL;DR

This paper investigates the decay process of unstable D-branes via light-like tachyon condensation in subcritical string theory, calculating decay rates and string emission using boundary state methods.

Contribution

It provides the first detailed calculation of closed string emission and open string pair production from light-like tachyon decay in a linear dilaton background.

Findings

Decay rate is finite in the open string UV region.

Decay rate depends on the tachyon profile in the IR region.

Open string pair production occurs during the decay process.

Abstract

In this paper closed string emission and open string pair production from the light-like rolling tachyon solution are calculated in subcritical string theory in the background of a linear dilaton. The rolling light-like tachyon represents the inhomogeneous decay of unstable D-brane. The decay rate is given by the imaginary part of annulus diagram which can be calculated using the boundary state/sigma-model method. It is found that the decay rate is finite in the open string ultraviolet region and depends on tachyon profile in the open string infrared region.