Full-Phase-Space Twist Expansion in Semileptonic and Radiative B-Meson Decays

Abstract

We study the Lambda_QCD/M_B corrections from subleading shape functions in inclusive B-meson decays. We propose a natural and smooth interpolation from the endpoint region to the full phase space, and derive expressions for the triple differential decay rate in B -> X_u l nu and the photon energy spectrum in B -> X_s gamma. Our results are valid to order Lambda_QCD/M_B for hadronic invariant masses of order Lambda_QCD M_B and to order Lambda_QCD^2/M_B^2 for larger hadronic masses. They allow a systematic investigation of the transition between the separate regimes of the local and nonlocal expansions, and can be used to study decay distributions in any kinematic variables. We consider several examples of interest and point out that a combined measurement of hadronic energy and invariant mass provides an alternative to the extraction of |V_ub| which is largely independent of shape function effects and in principle allows a higher accuracy than the combined measurement of leptonic and hadronic invariant masses. We perform the expansion directly in QCD light-cone operators, and give a discussion of the general basis of light-cone operators. Reparametrization invariance under the change of the light-cone direction reduces the number of independent shape functions. We show that differing previous results for the lepton energy spectrum obtained from different choices of light-cone coordinates are in agreement.

41 pages, 20 figures, v2: few references added, slightly extended discussion (2 figures added to illustrate m_b dependence), v3: final journal version

References in corpus (10)

• Factorization and Shape-Function Effects in Inclusive B-Meson Decays
• Global analysis of inclusive B decays
• Shape function effects in B -> X_s gamma and B -> X_u l nu decays
• Subleading Shape Functions in Inclusive B Decays
• A Complete Basis for Power Suppressed Collinear-Ultrasoft Operators
• Determination of the Branching Fraction for B --> Xc l nu Decays and of |Vcb| from Hadronic-Mass and Lepton-Energy Moments
• Subleading shape function contributions to the hadronic invariant mass spectrum in B -> X_u l νdecay
• Shape Function Effects in B -> X_c l ν_l
• The status of |Vub|
• Subleading Light-cone distributions functions in the decays Lambda(b) --> X(s) Gamma and Lambda(b) --> X(u) Lepton Anti-Nu

Cited by in corpus (18)

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• A Complete Basis of Helicity Operators for Subleading Factorization
• Reparameterization Invariant Collinear Operators
• Precise predictions for B -> Xc tau nu decay distributions
• Helicity Methods for High Multiplicity Subleading Soft and Collinear Limits
• Shape-Function Effects and Split Matching in B-> Xs l+ l-
• Precision Global Determination of the $B\to X_s\gamma$ Decay Rate
• Universality and m_X cut effects in B -> Xs l+ l-
• Nonperturbative m_X cut effects in B -> Xs l+ l- observables
• 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
• Shape Functions from B -> X_c \ell ν
• Subleading Shape-Function Effects and the Extraction of |V_ub|
• Mass relations among family members of quarks and leptons
• QCD Beyond Leading Power
• Semileptonic B Decays and Determination of |Vub|