Z → bb and Z → cc as tests of the standard model and the mass of the Higgs boson

We consider the decays Z → bb and Z → cc as tests of the Standard Model (SM). We find that Rb = 0.2145 and Rc = 0.1719. Comparing with recent experimental measurements, we find that Rb[suexp is too high by only (1.4σ) and Rcexp is too low by only (0.1σ).