Abstract:

The experimental determination of standard model parameters from processes involving hadrons is frustrated by the non-perturbative nature of QCD at low energies. I will show how effective field theories enable the separation of long distance non-perturbative physics from the short distance physics we try to measure. In many cases the long distance QCD effects are then independent of the process under consideration and can be determined experimentally. I will present two examples of this idea: The first is the determination of Vcb from inclusive, semileptonic B decays, which illustrates the level of precision that can be achieved using these ideas. The second example shows how the recently developed Soft Collinear Effective Theory can be used to understand non-perturbative effects in events involving highly energetic jets.