Eliminating the hadronic uncertainty

The standard model Lagrangian requires the values of the fermion masses, the Higgs boson mass, and three other experimentally well-measured quantities as input in order to become predictive. These are typically taken to be α, Gμ, and MZ. Using the first of these, however, introduces a hadronic contribution that leads to a significant error. If a quantity could be found that was measured at high energy with sufficient precision then it could be used to replace α as input. The level of precision required for this to happen is given for a number of precisely measured observables. The W boson mass must be measured with an error of ±13 MeV, ΓZ to 0.7 MeV, and polarization asymmetry ALR to ±0.002 that would seem to be the most promising candidate. The role of renormalized parameters in perturbative calculations is reviewed and the value for the electromagnetic coupling constant in the M bar S renormalization scheme that is consistent with all experimental data is obtained to be αM bar S-1(MZ2)=128.17