Rapidity resummation for<i>B</i>-meson wave functions

Shen, Yue-Long; Wang, Yuming

doi:10.1051/epjconf/20148000047

Cited by 4 publications

(2 citation statements)

References 21 publications

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“…It is evident that the standard momentum-space resummation technique cannot be applied to cope with this term which is independent of the factorization scale. Investigating resummation of such logarithm with the rapidity RG evolution equations [43][44][45][46] is apparently of conceptual interest and we will pursue this endeavour in a future work.…”

Section: The Lcsr Of λ B → λ Form Factors At O(α S )mentioning

confidence: 99%

Perturbative corrections to Λ b → Λ form factors from QCD light-cone sum rules

Wang

Shen

2016

J. High Energ. Phys.

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We compute radiative corrections to Λ b → Λ from factors, at next-to-leading logarithmic accuracy, from QCD light-cone sum rules with Λ b -baryon distribution amplitudes. Employing the diagrammatic approach factorization of the vacuum-to-Λ b -baryon correlation function is justified at leading power in Λ/m b , with the aid of the method of regions. Hard functions entering the factorization formulae are identical to the corresponding matching coefficients of heavy-to-light currents from QCD onto soft-collinear effective theory. The universal jet function from integrating out the hard-collinear fluctuations exhibits richer structures compared with the one involved in the factorization expressions of the vacuum-to-B-meson correlation function. Based upon the QCD resummation improved sum rules we observe that the perturbative corrections at O(α s ) shift the Λ b → Λ from factors at large recoil significantly and the dominant contribution originates from the next-to-leading order jet function instead of the hard coefficient functions. Having at hand the sum rule predictions for the Λ b → Λ from factors we further investigate several decay observables in the electro-weak penguin Λ b → Λ + − transitions in the factorization limit (i.e., ignoring the "non-factorizable" hadronic effects which cannot be expressed in terms of the Λ b → Λ from factors), including the invariant mass distribution of the lepton pair, the forward-backward asymmetry in the dilepton system and the longitudinal polarization fraction of the leptonic sector.

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Section: The Lcsr Of λ B → λ Form Factors At O(α S )mentioning

confidence: 99%

Perturbative corrections to Λ b → Λ form factors from QCD light-cone sum rules

Wang

Shen

2016

J. High Energ. Phys.

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“…Albeit the fact that factorization in a non-abelian gauge theory like QCD is by no means a trivial issue, collinear factorization for a number of interesting hard reactions, at leading power in 1/Q where Q is the typical hard scale for a given process, can be established with rigorous power counting schemes and standard assumptions. By contrast, transverse-momentum-dependent (TMD) factorization for hard exclusive processes based upon the theory of on-shell Sudakov form factor [1], with the original aim of avoiding the rapidity divergences in collinear factorization for the pion electromagnetic form factor at sub-leading power [2], turns out to be far more sophisticated conceptually due to the absence of a definite power counting scheme and to the emergence of lightcone singularities in the infrared subtraction, and this can be already partially recognized from the troubled history of TMD wave functions [3][4][5][6][7][8][9][10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Non-dipolar gauge links for transverse-momentum-dependent pion wave functions

Wang

2016

EPJ Web of Conferences

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Abstract. I discuss the factorization-compatible definitions of transverse-momentumdependent (TMD) pion wave functions which are fundamental theory inputs entering QCD factorization formulae for many hard exclusive processes. I will first demonstrate that the soft subtraction factor introduced to remove both rapidity and pinch singularities can be greatly reduced by making the maximal use of the freedom to construct the Wilson-line paths when defining the TMD wave functions. I will then turn to show that the newly proposed TMD definition with non-dipolar Wilson lines is equivalent to the one with dipolar gauge links and with a complicated soft function, to all orders of the perturbative expansion in the strong coupling, as far as the infrared behavior is concerned.

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QCD corrections toB→πform factors from light-cone sum rules

2015

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We compute perturbative corrections to B → π form factors from QCD light-cone sum rules with B-meson distribution amplitudes. Applying the method of regions we demonstrate factorization of the vacuum-to-B-meson correlation function defined with an interpolating current for pion, at one-loop level, explicitly in the heavy quark limit. The short-distance functions in the factorization formulae of the correlation function involves both hard and hard-collinear scales; and these functions can be further factorized into hard coefficients by integrating out the hard fluctuations and jet functions encoding the hard-collinear information. Resummation of large logarithms in the short-distance functions is then achieved via the standard renormalization-group approach. We further show that structures of the factorization formulae for f + Bπ (q 2 ) and f 0 Bπ (q 2 ) at large hadronic recoil from QCD light-cone sum rules match that derived in QCD factorization. In particular, we perform an exploratory phenomenological analysis of B → π form factors, paying attention to various sources of perturbative and systematic uncertainties, and extract |V ub | = 3.05 +0.54 −0.38 | th. ± 0.09| exp. × 10 −3 with the inverse moment of the B-meson distribution amplitude φ + B (ω) determined by reproducing f + Bπ (q 2 = 0) obtained from the light-cone sum rules with π distribution amplitudes. Furthermore, we present the invariant-mass distributions of the lepton pair for B → πℓν ℓ (ℓ = µ , τ ) in the whole kinematic region. Finally, we discuss non-valence Fock state contributions to the B → π form factors f + Bπ (q 2 ) and f 0 Bπ (q 2 ) in brief.

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Rapidity resummation forB-meson wave functions

Cited by 4 publications

References 21 publications

Perturbative corrections to Λ b → Λ form factors from QCD light-cone sum rules

Perturbative corrections to Λ b → Λ form factors from QCD light-cone sum rules

Non-dipolar gauge links for transverse-momentum-dependent pion wave functions

QCD corrections toB→πform factors from light-cone sum rules

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