Aspects of String Pertubation Theory

We will examine the only known example in which supersymmetry can be spontaneously broken in superstring perturbation theory, despite being unbroken at the tree-level. We will be able to detect the breaking of the supersymmetry by looking at the mass-splitting that arises as a one-loop effect affecting a chiral supermultiplet of the low-energy limit of the SO(32) heterotic superstring compactified in a Calabi-Yau manifold. We will not take any background in string theory for granted so a lot of effort will be made to introduce those aspects of string perturbation theory that are needed to understand the final computation, namely the 2 point correlation function that is intimately related to the mass-splitting in which we are interested.