R-Symmetry and the Topological Twist of N=2 Effective Supergravities of Heterotic Strings

الأصل · EN

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)× SO(2,n)/(SO(2) × SO(n)) R-symmetry with the specified properties is a continuous symmetry, but for the quantum corrected manifolds ST(n) a discrete R--group of electric--magnetic duality rotations is sufficient and we argue that it exists.