kT FACTORIZATION OF EXCLUSIVE B DECAYS

Both collinear factorization theorem 1 and kT factorization theorem 2,3 are the fundamental tools of perturbative QCD (PQCD), where kT denotes parton transverse momenta. In these theorems the amplitude for an exclusive process can be calculated as an expansion of αs(Q) and Λ/Q with Q being a large momentum transfer and Λ a small hadronic scale. Similarly, in the heavy quark limit mb → ∞, mb being the b quark mass, a B meson decay amplitude can be calculated as an expansion of αs(mb) and Λ/mb 4. A study of B meson decays is important for determining Standard Model parameters, such as the unitarity angles.