Nonperturbative effects on seven-brane Yukawa couplings.

We analyze nonperturbative corrections to the superpotential of seven-brane gauge theories on type IIB and F-theory warped Calabi-Yau compactifications. We show, in particular, that such corrections modify the holomorphic Yukawa couplings by an exponentially suppressed contribution, generically solving the Yukawa rank-one problem of certain F-theory local models. We provide explicit expressions for the nonperturbative correction to the seven-brane superpotential, and check that it is related to a noncommutative deformation to the tree-level superpotential via a Seiberg-Witten map.