Cohomological Yang-Mills theories on Kahler 3-folds

We study topological gauge theories with N-c = (2, 0) supersymmetry based o n stable bundles on general Kahler 3-folds. In order to have a theory that is well defined and well behaved, we consider a model based on an extension of the usual holomorphic bundle by including a holomorphic 3-form. The cor relation functions of the model describe complex 3-dimensional generalizati ons of Donaldson-Witten type invariants, We show that the path integral can be written as a sum of contributions from stable bundles and a complex 3-d imensional version of Seibeg-Witten monopoles. We study certain deformation s of the theory, which allow us to consider the situation of reducible conn ections. We shortly discuss situations of reduced holonomy. After dimension al reduction to a Kahler 2-fold, the theory reduces to Vafa-Witten theory. On a Calabi-Yau 3-fold, the supersymmetry is enhanced to N-c = (2, 2). This model map be used to describe classical limits of certain compactification s of (matrix) string theory. (C) 2001 Published by Elsevier Science B.V.