Instantons in string theory

Abstract

These proceedings from the second Caesar Lattes meeting in Rio de Janeiro 2015 are a brief introduction to how automorphic forms appear in the low energy effective action of maximally supersymmetric string theory. The explicit example of the R 4-interaction of type IIB string theory in ten dimensions is discussed. Its Fourier expansion is interpreted in terms of perturbative and non-perturbative contributions to the four graviton amplitude. HIGHER DERIVATIVE CORRECTIONS TO GENERAL RELATIVITY String theory offers an ultraviolet completion to general relativity. A good way of thinking about this is from the perspective of the low energy effective action. 1 A vector field, for example, with a vev would single out a distinguished direction in spacetime which would depend on the observer. 2 The vev of the axion plays a role analogous to that of the θ-angle in Yang-Mills theory.