International journal of modern physics. A, Particles and fields, gravitation, cosmology vol:12 issue:2 pages:379-418
We discuss R symmetries in locally supersymmetric N = 2 gauge theories coupled to hypermultiplets which can be thought of as effective theories of heterotic superstring models. In this type of supergravities a suitable R symmetry exists and can be used to topologically twist the theory: the vector multiplet containing the dilaton-axion field has different R charge assignments with respect to the other vector multiplets. Correspondingly a system of coupled instanton equations emerges, mixing gravitational and Yang-Mills instantons with triholomorphic hyperinstantons and axion instantons. For the tree level classical special manifolds ST(n) = SU(1, 1)/U(1) x SO(2,n)/[SO(2) x SO(n)] R symmetry with the specified properties is a continuous symmetry, but for the quantum-corrected manifolds <(ST)over cap (n)> a discrete R group of electric-magnetic duality rotations is sufficient and we argue that it exists.