01270nas a2200133 4500008004300000245010000043210006900143520080600212100002001018700002401038700002401062700001401086856003601100 2009 en_Ud 00aDecoupling A and B model in open string theory: topological adventures in the world of tadpoles0 aDecoupling A and B model in open string theory topological adven3 aIn this paper we analyze the problem of tadpole cancellation in open topological strings. We prove that the inclusion of unorientable worldsheet diagrams guarantees a consistent decoupling of A and B model for open superstring amplitudes at all genera. This is proven by direct microscopic computation in Super Conformal Field Theory. For the B-model we explicitly calculate one loop amplitudes in terms of analytic Ray-Singer torsions of appropriate vector bundles and obtain that the decoupling corresponds to the cancellation of D-brane and orientifold charges. Local tadpole cancellation on the worldsheet then guarantees the decoupling at all loops. The holomorphic anomaly equations for open topological strings at one loop are also obtained and compared with the results of the Quillen formula.1 aBonelli, Giulio1 aPrudenziati, Andrea1 aTanzini, Alessandro1 aJie, Yang uhttp://hdl.handle.net/1963/3632