We study \Omega-deformation of B-twisted gauge theories in two dimensions. As
an application, we construct an \Omega-deformed, topologically twisted
five-dimensional maximally supersymmetric Yang-Mills theory on the product of a
Riemann surface Σ and a three-manifold M, and show that when Σ
is a disk, this theory is equivalent to analytically continued Chern-Simons
theory on M. Based on these results, we establish a correspondence between
three-dimensional N=2 superconformal theories and analytically
continued Chern-Simons theory. Furthermore, we argue that there is a mirror
symmetry between {\Omega}-deformed two-dimensional theories.Comment: 26 pages. v2: the discussion on the boundary condition for vector
multiplet improved, and other minor changes mad