Interfaces in Conformal Field Theory and String Theory

Abstract

In the present work we start from the classification of interfaces (preserving the whole current algebra) between bosonic CFTs and their supersymmetric extention and apply the interface analysis to superstring theory compactified on tori. We dedicate attention to the case of heterotic string theory, for which no D-branes are known to exist, but nevertheless we can easily write interfaces (corresponding to D-branes of the doubled theory). Here the peculiar features are the difference in left and right field content and the presence only of right supersymmetry. We show this forces supersymmetric (conformal) interfaces to be topological (i.e. acting separately on left and right fields). These are very special interfaces, with the property they can be freely moved (and deformed) on the world-sheet, provided they do not cross any field insertion