CP violation and supersymmetry-breaking in superstring models

In this thesis I discuss aspects of the phenomenology of heterotic string, theory, using low-energy effective supergravity models. I investigate the origin of CP violation, the implications for low-energy physics of the modular invariance of the theory, supersymmetry-breaking via gaugino condensation in a hidden sector, and the interplay between these topics. I review the theory of CP violation and the problem of CP violation in supersymmetry phenomenology. In a scenario where the origin of CP violation lies in the compactification of the extra dimensions of string theory, I present simple models which include a duality symmetry acting on the compactification modulus and on observable fields. I show how the structure of the theory affects CP-violating observables, and discuss the effect of such a symmetry on low-energy physics in general. I present a detailed investigation of supersymmetry-breaking by gaugino condensation in supergravity, in particular as applied to the stabilisation of string moduli. For hidden sectors with or without matter I calculate corrections to the usual formulae for the scalar potential and soft supersymmetry-breaking terms. I discuss the phenomenological implications of these corrections and show that they may affect the value of the compactification modulus. and consequently the prospects for predictions of CP violation in string models. (author)SIGLEAvailable from British Library Document Supply Centre-DSC:DXN036508 / BLDSC - British Library Document Supply CentreGBUnited Kingdo