Lepton electric dipole moments in supersymmetric theories

Abstract

An electric dipole moment (EDM) of an elementary particle is a quantum effect which vanishes unless the CP symmetry, the combination of charge conjugation and parity symmetries, of the underlying theory is broken. In the Standard Model of particle physics, the parameter responsible for CP violation is only the complex phase in the Cabibbo-Kobayashi-Maskawa matrix, and the pre dicted value of thelectron EDM is many orders of magnitude smaller than the experimental bounds. It is thus tempting to have the theories that can predict larger values of the electron EDM. One such theory is a supersymmetric extension of the Standard Model, known as the Minimal Supersymmetric Standard Model,which contains more CP violation parameters. In this thesis, the electron EDM is calculated at the one-loop level of Quantum Field Theory, in the framework of the constrained Minimal Super symmetric Standard Model with two CP-violating phases. It is found that the electron EDM receives contributions from neutralino and chargino exchange diagrams. With the experimental bounds of the electron EDM, the obtained formula for the EDM can be used to constrain some unknown parameters of the theory.