Subleading Shape Functions and the Determination of |V_{ub}|

Abstract

It is argued that the dominant subleading shape-function contributions to the endpoint region of the charged-lepton energy spectrum in B -> X_u l nu decays can be related in a model-independent way to an integral over the B -> X_s gamma photon spectrum. The square root of the fraction of B -> X_u l nu events with charged-lepton energy above E_0=2.2 GeV can be calculated with a residual theoretical uncertainty from subleading shape-function effects that it safely below the 10% level. These effects have therefore a minor impact on the determination of |V_{ub}|.

8 pages, 1 figure. Final version to appear in Physics Letters B. By a smarter choice of weight function, m_b and lambda_1 have been eliminated from the final results. A paragraph has been added mentioning the potentially sizeable uncertainty due to duality violations and spectator-dependent effects. The discussion of the results obtained in refs. [7,8] has been made more accurate

References in corpus (7)

• Soft-Collinear Factorization in Effective Field Theory
• Branching Fraction and Photon Energy Spectrum b -> s gamma
• Quark mass effects in B -> Xs gamma
• Improved Measurement of |V_ub| with Inclusive Semileptonic B Decays
• Non-factorization effects in heavy mesons and determination of |V_{ub}| from inclusive semileptonic B decays
• Enhanced subleading structure functions in semileptonic B decay
• Note on the Extraction of |V_{ub}| using Radiative B Decays

Cited by in corpus (19)

• CP Violation and the CKM Matrix: Assessing the Impact of the Asymmetric B Factories
• Factorization and Shape-Function Effects in Inclusive B-Meson Decays
• Theory of Charmless Inclusive B Decays and the Extraction of V_{ub}
• Subleading Shape Functions in Inclusive B Decays
• Factorization for Power Corrections to B->Xs gamma and B-> Xu e nu
• Subleading Power Factorization with Radiative Functions
• Measurement of |V_ub| near the endpoint of the electron momentum spectrum from semileptonic B-meson decays
• Proposal for a Precision Measurement of |Vub|
• Subleading Jet Functions in Inclusive B Decays
• A two-loop relation between inclusive radiative and semileptonic B-decay spectra
• Subleading shape function contributions to the hadronic invariant mass spectrum in B -> X_u l νdecay
• Refactorisation in subleading $\bar{B}\to X_s\gamma$
• Shape-function independent relations of charmless inclusive B-decay spectra
• Towards the Anomalous Dimension to Order Lambda_QCD/m_b for Phase Space Restricted B --> X(u) ell anti-nu and B --> X(s) gamma
• Radiative B Decays: Standard Candles of Flavor Physics
• Soft-Collinear Factorization and Sudakov Resummation of Heavy Meson Decay Amplitudes with Effective Field Theories
• Determination of |Vub|
• QCD Beyond Leading Power
• Measurements of |Vub| and |Vcb| from CLEO