Exact one-loop evolution invariants in the standard model

Guided by considerations of flavor symmetry, we construct a set of exact standard model renormalization group evolution invariants which link quark masses and mixing parameters. We examine their phenomenological implications and infer a simple combination of Yukawa coupling matrices which plays a unique role in the standard model, suggesting a possible new insight into the observed spectrum of quark masses. Our evolution invariants are readily generalized to the leptons in the case of Dirac neutrinos, but do not appear to be relevant for either quarks or leptons in the minimal supersymmetric standard model.