Rolling Tachyon

Abstract

We discuss construction of classical time dependent solutions in open string\n(field) theory, describing the motion of the tachyon on unstable D-branes.\nDespite the fact that the string field theory action contains infinite number\nof time derivatives, and hence it is not a priori clear how to set up the\ninitial value problem, the theory contains a family of time dependent solutions\ncharacterized by the initial position and velocity of the tachyon field. We\nwrite down the world-sheet action of the boundary conformal field theories\nassociated with these solutions and study the corresponding boundary states.\nFor D-branes in bosonic string theory, the energy momentum tensor of the system\nevolves asymptotically towards a finite limit if we push the tachyon in the\ndirection in which the potential has a local minimum, but hits a singularity if\nwe push it in the direction where the potential is unbounded from below.\n