QCD Sum Rules on the Light-Cone, Factorisation and SCET

Abstract

The accurate calculation of weak heavy-to-light form factors is crucial for the determination of CKM matrix elements from experimental data on B decays. In SCET, the soft-collinear effective theory, these form factors can, in the heavy quark limit, be split into a factorisable part that is calculable in perturbation theory, and a nonfactorisable part that observes certain spin-symmetries. I discuss the relation between the SCET factorisation formulas and the heavy quark limit of the corresponding QCD sum rules on the light-cone. I also analyse the numerical size of factorisable and nonfactorisable parts and corrections suppressed by powers of the b quark mass.