Open Superstring Theory and Superalgebra of the Brane Antibrane System

Open superstring theory is formulated in terms of a nondegenerate supertranslation algebra. Spontaneously broken supersymmetry is described by the auxiliary fields which arise as parameters of this algebra and lead to a tachyonic open superstring. The anticommutator of two supercharges of the tachyonic superstring does not contain the zero eigenvalue and so this string is not a BPS state. Brane-antibrane annihilation scenarios are described by these superalgebras defined on the sum of world-volumes of a D-brane, an anti-D-brane and a tachyonic superstring