Renormalon analysis of heavy-light exclusive B decays - art. no. 034009

We study two-body exclusive decays of the form (B) over bar-->(DL)-L-(*) (L = pi,rho,...) in the heavy-quark limit. We perform a renormalon analysis of such processes to determine the order at which nonperturbative factorizati on-breaking power corrections enter the amplitude. We find that a class of leading power corrections to the color octet matrix element, of O(Lambda (Q CD)/m(b)), vanishes in the limit of a symmetric light meson parton distribu tion function. We discuss the phenomenological significance of this result.