Omega-deformed Seiberg-Witten effective action from the M5-brane

We obtain the leading order corrections to the effective action of an M5-brane wrapping a Riemann surface in the eleven-dimensional supergravity Ω-background. The result can be identified with the first order ϵ-deformation of the Seiberg-Witten effective action of pure SU(2) gauge theory. We also comment on the second order corrections and the generalization to arbitrary gauge group and matter content.