Brane - Antibrane as a Defect of Tachyon Condensation
  In a tachyon effective field theory of a non-BPS brane, we construct a classical solution representing a parallel brane-antibrane. The solution is made of a kink and an antikink placed at antipodal points of S^1. Estimation of the brane energy suggests an excitation of a string connecting the two branes, even though the theory is Abelian. We performed fluctuation analysis around the obtained solution, and find the structure of the supersymmetry breaking by the co-existence of the brane and the antibrane. We discuss possible processes of the pair-annihilation of the brane defect. 
Koji Hashimoto, Norisuke Sakai