Rolling tachyons for separated brane-antibrane systems

International audienceWe consider tachyon condensation between a D-brane and an anti-D-brane in superstring theory, when they are separated in their common transverse directions. A simple rolling tachyon solution, which describes the time evolution of the process, is studied from the point of view of boundary conformal field theory. By computing the boundary beta functions of the system, one finds that this theory is conformal and hence corresponds to an exact solution of the string theory equations of motion. By contrast, the time-reversal-symmetric rolling tachyon is not conformal. These results put constraints on the space-time effective actions for the system