Perturbative QCD study of the B→K* γ decay

We apply the perturbative QCD factorization theorem developed recently for nonleptonic heavy meson decays to the radiative decay B→K* γ. In this formalism the evolution of the Wilson coefficients from the W boson mass down to the characteristic scale of the decay process is governed by the effective weak Hamiltonian. The evolution from the characteristic scale to a lower hadronic scale is formulated by the Sudakov resummation. In addition to computing the dominant contribution arising from the magnetic-penguin operator O₇, we also calculate the contributions of four-quark operators. By fitting our prediction for the branching ratio of the B→K* γ decay to the CLEO data, we determine the B meson wave function that possesses a sharp peak at a low momentum fraction.