Target Space Approach to Closed String Tachyons

Abstract

We use the low energy effective theory of string theory to investigate condensations of closed string tachyons propagating in the bulk. The c-function is related to the total energy of the system via the effective action. A possible modification of the c-theorem is discussed. We also deduce endpoints of the decays by investigating scalar potential of gauged supergravities. A string theory in the flat spacetime would be a possible endpoint.