Factorization for power corrections to B→Xsγ and B→Xul(v)over-bar

We derive factorization theorems for Lambda(QCD)/m(b) power corrections to inclusive B-decays in the endpoint region, where m(X)(2) similar to m(b)Lambda(QCD). In B -> Xul (v) over bar our results are for the full triply differential rate. A complete enumeration of Lambda(QCD)/m(b) corrections is given. We point out the presence of new Lambda(QCD)/m(b)-suppressed shape functions, which arise at tree level with a 4 pi-enhanced coefficient, and show that these previously neglected terms induce an additional significant uncertainty for current inclusive methods of measuring I Vu 1, 1 that depend on the endpoint region of phase space. (c) 2005 Elsevier B.V. All rights reserved.