title: Proof of factorization for B --> D pi.
abstract: We prove that the matrix elements of four fermion operators mediating the decays B macro (0)-->D(+)pi(-) and B--->D(0)pi(-) factor into the product of a form factor describing the B-->D transition and a convolution of a short distance coefficient with the nonperturbative pion light-cone wave function. This is shown to all orders in alpha(s), with corrections suppressed by factors of 1/m(b), 1/m(c), and 1/E(pi). It is not necessary to assume that the pion state is dominated by the qq macro Fock state.
authors.affiliation: Physics Department, University of California at San Diego, La Jolla, California 92093.
authors.forename: C W
authors.initials: CW
authors.lastname: Bauer
authors.forename: D
authors.initials: D
authors.lastname: Pirjol
authors.forename: I W
authors.initials: IW
authors.lastname: Stewart