M5-branes, Special Lagrangian Submanifolds and sigma-models

We study M-theory fivebranes wrapped on Special Lagrangian submanifolds ($\S_n$) in Calabi-Yau three- and fourfolds. When the M5 wraps a four-cycle, the resulting theory is a two-dimensional domain wall embedded in three-dimensional bulk with four supercharges. The theory on the wall is specified in terms of the geometry of the CY manifold and the cycle $\S_4$. It is chiral and anomalous, however the presence of a three-dimensional gravitational Chern-Simons terms with a coefficient that jumps when crossing the wall allows to cancel the anomaly by inflow. Kahler manifolds of special type, where the potential depends only on the real part of the complex coordinate, are shown to emerge as the target spaces of two-dimensional sigma-models when the M5 is wrapped on $\S_3 \times S^1$, thus providing a physical realization of some recent symplectic construction by Hitchin.