Subleading Shape-Function Effects and the Extraction of |Vub|
Abstract
We derive a class of formulae relating moments of B -> Xu l nu to B -> Xs gamma in the shape function region, where mX2 ~ mb LambdaQCD. We also derive an analogous class of formulae involving the decay B -> Xs l+ l-. These results incorporate LambdaQCD/mb power corrections, but are independent of leading and subleading hadronic shape functions. Consequently, they enable one to determine |Vub|/|Vtb Vts*| to subleading order in a model-independent way.
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