Brane/antibrane configurations in type IIA and M-theory

We investigate the relation between large N duality applied to systems of D5's and D5's wrapping vanishing cycles of local CY in type IIB and M-theory lifts of the NS5/D4/D4 systems in type HA to which they are related by T-duality. Through a simple example based on a local CY constructed using an A(2) singularity, we review this well-known correspondence in the supersymmetric setting and describe the manner in which it generalizes when antibranes are added. Agreement between the IIB and HA pictures, which supports the assertion that N = 2 supersymmetry is spontaneously broken in these systems at string tree level, is demonstrated when g(s) << 1. Novel nonholomorphic features can arise away from this regime and their physical origin is discussed. This note is based on talks given at KITP, Harvard University, TIFR, the University of Tokyo at Hongo, the 2007 Les Houches Summer School, and the 2007 Simons Workshop, is based on work done in collaboration with K. Papadodimas and M. Shigemori, and contains some previously unpublished results.