We discuss the use of two QCD based effective field theories in determining parametersof the standard model. Heavy Quark Effective theory provides a framework forstudying the weak decays of the B meson. We calculate the B → Xclv decay rateto second nonvanishing order in the HQET expansion and compare the theoreticalprediction to experimental data. This allows us to determine the b and c pole quarkmasses and the weak mixing angle Vcb.
Nonrelativistic QCD is an effective field theory in which bound states of two heavyquarks can be analyzed conveniently. We use this approach to compute the leadingrelativistic corrections to the decay of S-wave quarkonia. These corrections can beexpressed in terms of the leading order result and the quark pole mass. Includingcolor octet contributions and the first relativistic corrections, we extract the valueof αs from low energy data. We also show that the color octet contributions to thedecay rates are not negligible.
