Effective Tachyon Dynamics in Superstring Theory

Abstract

A recently proposed \ell=\infty field theory model of tachyon dynamics for unstable bosonic D-branes has been shown to arise as the two-derivative truncation of (boundary)-string field theory. Using an \ell\to \infty limit appropriate to stable kinks we obtain a model for the tachyon dynamics on unstable D-branes or D-brane anti-D-brane pairs of superstring theory. The tachyon potential is a positive definite even function of the tachyon, and at the stable global minima there is no on-shell dynamics. The kink solution mimics nicely the properties of stable D-branes: the spectrum of the kink consists of infinite levels starting at zero mass, with spacing double the value of the tachyon mass-squared. It is natural to expect that this model will arise in (boundary) superstring field theory.

Figures (1)

• Figure 1: The profile $\overline\phi (x) = \hbox{erf} (x/2)$ of the stable kink representing a D-brane. In the field variable $T$ used in (\ref{['themodel']}) we have $\overline T (x) = x/2$.