Hadronic B decays from SCET

The standard model (SM) of particle physics has proven to hold up against any experimental tests it has been subjected to so far. The SM has several striking features for which no underlying principle has been experimentally confirmed to this date. First, the SM requires the scale of electro-weak symmetry breaking to be of order a few hundred GeV, which is many orders of magnitude below the only fundamental scale of nature we know of, the Planck scale. Second, to explain the masses and flavor violating transitions of fermions requires the fundamental Yukawa matrices to satisfy a very particular scaling, for which no satisfactory symmetry or other underlying principle has been found so far. While the scale of electro-weak symmetry breaking is known from the measured properties of gauge interactions, the scale of flavor violation could be completely unrelated to that scale. However, many models of new physics which address the electro-weak scale also give additional contributions to flavor physics. Thus, precise measurements of flavor and CP violating observables can severely constrain possible models of electro-weak symmetry breaking. Since the standard model predicts the short distance couplings of quarks to one another, while experimental measurements are done with hadrons, one needs to understand long distance QCD effects on the measured quantities to extract the underlying physics. It is the purpose of this talk to discuss how this separation between long and short distance physics can be achieved using effective theories. The effective theory that is applicable to the non-leptonic B decays to two light mesons, as we are concerned with here, is the soft-collinear effective theory (SCET) [1].