Open String Tachyon in Supergravity Solution

We study the tachyon condensation of the DD̄-brane system with a constant tachyon vev in the context of classical solutions of the Type II supergravity. We find that the general solution with the symmetry ISO(1, p)×SO(9−p) (the three-parameter solution) includes the extremal black p-brane solution as an appropriate limit of the solution with fixing one of the three parameters (c1). Furthermore, we compare the long distance behavior of the solution with the massless modes of the closed strings from the boundary state of the DD̄-brane system with a constant tachyon vev. We find that we must fix c1 to zero and the only two parameters are needed to express the tachyon condensation of the DD̄-brane system. This means that the parameter c1 does not correspond to the tachyon vev of the DD̄-brane system. E-mail: [email protected] E-mail: [email protected] E-mail: [email protected]