I shall talk about a class eight derivative interactions in the effective action of type IIB string theory compactified on T^2. These 1/2 BPS interactions have moduli dependent couplings. I shall impose the constraints of supersymmetry to show that each of these couplings satisfy a first order differential equation on moduli space which relate it to other couplings in the same supermuliplet. The couplings which only depend on the SO(2)\SL(2,R) moduli satisfy Laplace equation on moduli space. On the other hand, the ones which only depend on the SO(3)\SL(3,R) moduli are far more complicated, and satisfy Poisson equation on moduli space, where the source terms are given by other couplings in the same supermultiplet.
view more