Supersymmetric renormalization of the CKM matrix and new constraints on the squark mass matrices

We compute the finite renormalization of the Cabibbo-Kobayashi-Maskawa matrix induced by gluino-squark diagrams in the minimal supersymmetric standard model with nonminimal sources of flavor violation. Subsequently we derive bounds on the flavor-off-diagonal elements of the squark mass matrices by requiring that the radiative corrections to the Cabibbo-Kobayashi-Maskawa elements do not exceed the experimental values. Our constraints on the associated dimensionless quantities δijdLR, j>i, are stronger than the bounds from flavor-changing neutral current (FCNC) processes if the gluino and squarks are heavier than 500 GeV. Our bound on |δ12uLR| is stronger than the FCNC bound from D-D mixing for superpartner masses above 900 GeV. We further find a useful bound on |δ13uLR|, for which no FCNC constraint is known. Our results imply that it is still possible to generate all observed flavor violation from the soft supersymmetry-breaking terms without conflicting with present-day data on FCNC processes. We suggest that a flavor symmetry renders the Yukawa sector flavor-diagonal and the trilinear supersymmetry-breaking terms are the spurion fields breaking this flavor symmetry. We further derive the dominant supersymmetric radiative corrections to the couplings of charged-Higgs bosons and charginos to quarks and squarks.