Die u:cris Detailansicht:
Factorization and dispersion relations for radiative leptonic B decay
- Autor(en)
- Yu-Ming Wang
- Abstrakt
Applying the dispersion approach we compute perturbative QCD corrections to the power suppressed soft contribution of B → γℓν at leading twist. QCD factorization for the B → γ
* form factors is demonstrated explicitly for the hard-collinear transverse polarized photon at one loop, with the aid of the method of regions. While the one-loop hard function is identical to the matching coefficient of the QCD weak current ūγ
μ ⊥(1 − γ
5)b in soft-collinear effective theory, the jet function from integrating out the hard-collinear fluctuations differs from the corresponding one entering the factorization formula of B → γℓν, due to the appearance of an additional hard-collinear momentum mode. Furthermore, we evaluate the sub-leading power contribution to the B → γ form factors from the three-particle B-meson distribution amplitudes (DAs) at tree level, with the dispersion approach. The soft contribution to the B → γ form factors from the three-particle B-meson DAs is shown to be of the same power compared with the corresponding hard correction, in contrast to the two-particle counterparts. Numerically the next-to-leading-order QCD correction to the soft two-particle contribution in B → γ form factors will induce an approximately (10 ∼ 20)% shift to the tree-level contribution at λ
B(μ
0) = 354 MeV. Albeit of power suppression parametrically, the soft two-particle correction can decrease the leading power predictions for the B → γ form factors by an amount of (10 ∼ 30)% with the same value of λ
B(μ
0). Employing the phenomenological model of the three-particle B-meson DAs inspired by a QCD sum rule analysis, the three-particle contribution to the B → γ form factors is predicted to be of O(1%), at leading order in α
s, with the default theory inputs. Finally, we explore theory constraints on the inverse moment of the leading-twist B-meson DA λ
B from the recent Belle measurements of the partial branching fractions of B → γℓν, taking into account the newly computed contributions to the B → γ form factors at subleading power.
- Organisation(en)
- Teilchenphysik
- Externe Organisation(en)
- Nankai University
- Journal
- Journal of High Energy Physics
- Band
- 2016
- Anzahl der Seiten
- 33
- ISSN
- 1029-8479
- DOI
- https://doi.org/10.1007/JHEP09(2016)159
- Publikationsdatum
- 09-2016
- Peer-reviewed
- Ja
- ÖFOS 2012
- 103012 Hochenergiephysik
- Schlagwörter
- ASJC Scopus Sachgebiete
- Nuclear and High Energy Physics
- Link zum Portal
- https://ucrisportal.univie.ac.at/de/publications/4c3750f9-91b7-4e83-8ca0-b60ebe25a89f