Metric Reduction in Generalized Geometry and Balanced Topological Field Theories

The recently established metric reduction in generalized geometry is encoded in 0-dimensional supersymmetric $\sigma$-models. This is an example of balanced topological field theories. To find the geometric content of such models, the reduction of Bismut connections is studies in detail. Generalized K$\ddot{a}$hler reduction is briefly revisited in this formalism and the generalized K$\ddot{a}$hler geometry on the moduli space of instantons on a generalized K$\ddot{a}$hler 4-manifold of even type is thus explained formally in a topological field theoretic way.