Mixing-matrix renormalization revisited

We study the renormalization of normal mixing matrices, which include hermitian and unitary matrices as particular cases. We give a minimal, multiplicative parameterization of counterterms, and compute the renormalized Lagrangian to one-loop order in several simple models with N species of fermions, both in on-shell and MS schemes. In the on-shell scheme the mass-degenerate case is considered separately. (orig.)