Intersecting Dp-branes often give rise to chiral fermions living on their intersections. We study the construction of four-dimensional chiral gauge theories by considering configurations of type IIA D6-branes wrapped on non-trivial 3-cycles on T$^6$. The gauge theories on the four non-compact dimensions of the brane world-volume are generically chiral and non-supersymmetric. We analyze consistency conditions (RR tadpole cancellation) for these models, and their relation to four-dimensional anomaly cancellation. Cancellation of U(1) gauge anomalies involves a Green-Schwarz mechanism mediated by RR fields. This class of models is of potential phenomenological interest, and we construct examples of SU(3) x SU(2) x U(1) three-generation models.

Institute for Advanced Study, Princeton