The Soft-Collinear Effective Field Theory

In general, to understand hadronic uncertainties we need a separation of short p ∼ Q and long p ∼ ΛQCD distance fluctuations. For processes in QCD with momentum transfers Q ≫ ΛQCD, the short distance part is calculable in terms of Wilson coefficients or hard scattering functions. The long distance contributions can be arranged into universal non-perturbative matrix elements which can be extracted from data or calculated on the lattice. This process of separating short and long distance fluctuations is sometimes referred to as factorization. In B physics a proper understanding of hadronic uncertainties is crucial, partially since the size of typical expansion parameters ΛQCD/mb, ΛQCD/mc, or √