On the Inclusive Determination of V_{ub} from the Lepton Invariant Mass Spectrum

Abstract

Bauer, Ligeti and Luke have recently proposed a new method for measuring |V_{ub}| in inclusive semileptonic B decays, using a cut on the lepton invariant mass to discriminate against b->c transitions. We investigate the structure of the heavy-quark expansion for this case and show that to all orders the magnitude of the leading perturbative and nonperturbative corrections is controlled by a hadronic scale mu_c=O(m_c) depending on the minimal value of q^2. These corrections can be analyzed using a modified version of the heavy-quark expansion (``hybrid expansion''). We find that the theoretical uncertainty in the extraction of |V_{ub}| is a factor 2.5 larger than previously estimated, which allows for a determination with 10% accuracy.

19 pages, 8 figures

References in corpus (2)

• Perturbative heavy quark-antiquark systems
• Nonperturbative corrections to B -> X_s l^+ l^- with phase space restrictions

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