Confinement and Non-perturbative Tachyons in Brane-Antibrane Systems

We present a worldvolume effective action suitable for the study of the confined phase of a Dp-anti-Dp system at weak coupling. We identify the mechanism by which the fundamental string arises from this action as a confined electric flux string when the Dp and the anti-Dp annihilate. We construct an explicit dual action, more suitable for the study of the strong coupling regime, and show that it realizes a generalized Higgs-Stueckelberg phase for the (relative) (p-2)-form field dual to the (overall) BI vector. This is the mechanism put forward by Yi and collaborators based on duality arguments in order to explain the breaking of the overall U(1) gauge group at strong coupling. Indeed, in our dual description the Goldstone boson is a (p-3)-form magnetically charged with respect to the overall BI vector field. This indicates that the condensing tachyonic objects originate from open D(p-2)-branes stretched between the brane and the anti-brane. Our results provide an explicit realization of the breaking of the overall U(1) gauge group perturbatively, in a way consistent with the duality symmetries of String Theory.