| Two of the major questions left unanswered by the Standard Model of particle physics have to do with hierarchies of mass scales. The first is the flavor problem: what determines the masses of the quarks and leptons, and why do they span such a large range, e.g. why is the top quark 3 ;Theories with weak scale supersymmetry offer a partial solution to the gauge hierarchy problem by stabilising the weak scale against radiative corrections. It is natural, then, to consider the flavor problem in a supersymmetric context, in which the flavor-changing constraints on the superpartner spectrum also have to be considered. Furthermore, some mechanism for dynamical supersymmetry breaking, together with the transmission of this breaking to the superpartners, is needed to explain the origin of the weak scale. These issues provide the motivation for the work in this thesis.;In the context of supersymmetric theories with minimal particle content, we construct theories of flavor based on spontaneously broken flavor symmetries where the first generation fermion masses vanish at tree level but are generated radiatively. The flavor symmetries also offer a solution to the supersymmetric flavor-changing problem.;We next construct a general framework for flavor symmetry breaking. All scales in the theory, including the scales of flavor and electroweak symmetry breaking, are triggered by the dynamical breakdown of supersymmetry at low energies.;In a different direction, we consider the possibility of solving the supersymmetric flavor-changing problem by pushing up the masses of the superpartners high enough to decouple their effects. In many cases, we uncover severe difficulties with this approach.;If superpartners are discovered, in addition to their masses there will be many new supersymmetric flavor mixing matrices to be measured. Some of these matrices violate lepton flavor conservation, and we explore how they may be probed at future ;Finally, we turn to dynamical supersymmetry breaking in the context of theories where this breaking is transmitted to the superpartners by the Standard Model gauge interactions, solving the supersymmetric flavor-changing problem. While this basic idea is appealing, all explicit realisations of these models in the literature are quite complicated. We present a general scheme (together with some of its generic difficulties) for simplifying the structure of these theories. |
