Dijkgraaf, RobbertHollands, LotteSulkowski, PiotrVafa, Cumrun2012-02-102008Dijkgraaf, Robbert, Lotte Hollands, Piotr Sulkowski, and Cumrun Vafa. 2008. Supersymmetric gauge theories, intersecting branes and free fermions. Journal of High Energy Physics 2008(02): 106.1029-8479http://nrs.harvard.edu/urn-3:HUL.InstRepos:8152243We show that various holomorphic quantities in supersymmetric gauge theories can be conveniently computed by configurations of D4-branes and D6-branes. These D-branes intersect along a Riemann surface that is described by a holomorphic curve in a complex surface. The resulting I-brane carries two-dimensional chiral fermions on its world-volume. This system can be mapped directly to the topological string on a large class of non-compact Calabi-Yau manifolds. Inclusion of the string coupling constant corresponds to turning on a constant \(B\)-field on the complex surface, which makes this space non-commutative. Including all string loop corrections the free fermion theory is elegantly formulated in terms of holonomic \(D\)-modules that replace the classical holomorphic curve in the quantum case.en-UStopological stringsD-branesstring dualityJournal Article2012-02-1010.1088/1126-6708/2008/02/106