Heterotic–type-I duality, D instantons, and anN=2AdS-CFT correspondence

Abstract

D-instanton effects are studied for the type-IIB orientifold ${T}^{2}/(\ensuremath{-}{1)}^{{F}_{L}}\ensuremath{\Omega}I$ of Sen using the type-I--heterotic duality. An exact one loop threshold calculation of ${t}_{8}\mathrm{tr}{F}^{4}$ and ${t}_{8}(\mathrm{tr}{F}^{2}{)}^{2}$ terms for the heterotic string on ${T}^{2}$ with Wilson lines breaking SO(32) to $\mathrm{SO}{(8)}^{4}$ is related to D-instanton-induced terms in the world volume of D7 branes in the orientifold. Introducing D3 branes and using the AdS-CFT correspondence in this case, these terms are used to calculate Yang-Mills instanton contributions to four point functions of the large ${N}_{c}$ limit of $N=2$ $\mathrm{USp}{(2N}_{c})$ SYM theory with four fundamental and one antisymmetric tensor hypermultiplets.