Flavor structure leading to hierarchical Yukawa couplings and Supersymmetry breaking

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Understanding the origin of fermion masses and mixing angles is one of important issues in particle physics. Within the framework of supersymmetric models, a mechanism to lead to realistic Yukawa matrices, in general, affects sfermion masses as well as the so-called A-terms. There are stringent experimental bounds on degeneracies of these SUSY breaking terms through FCNC processes. Taking into account these points, we have studied several types of flavor mechanisms.One type of flavor mechanisms which we have studied is supersymmetric standard models coupled with superconformal sectors, which have superconformal fixed points. In this type of models, superconformal dynamics generates large anomalous dimensions leading to hierarchically suppressed Yukawa couplings and at the same time controls sfermion masses so as to make them degenerate. Also we have studied flavor mechanism with 5D AdS background, which leads to the same result as the superconformal approach.We have also studied the model, which has S_3 symmetry as a flavor symmetry. Such symmetry has been studied in the literature, but it is broken at high energy. However, what is new in our model is that we extend the Higgs sector and impose the S_3 symmetry to the Higgs sector, too. The S_3 symmetry is broken around the electroweak scale. Such symmetry play a role in controlling SUSY breaking terms, so as to be consistent with experimental bounds on FCNC processes.Furthermore, we have also calculated Yukawa couplings in heterotic orbifold models including several moduli, e.g. continuous Wilson line moduli. One of our important results is that only the imaginary part of Kahler moduli contributes the physical CP phase in the Yukawa sector, while the other moduli, e.g. continuous and discrete Wilson lines do not contribute.