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. Besides 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.Comment: 17 pages, 4 figures; version to appear in Phys. Rev.