paper

Gluonic contribution to form factors

arXiv:hep-ph/0609165 · doi:10.1103/PhysRevD.74.074024

Abstract

We calculate the flavor-singlet contribution to the transition form factors from the gluonic content of the meson in the large-recoil region using the perturbative QCD approach. The formulation for the - mixing in the quark-flavor and singlet-octet schemes is compared, and employed to determine the chiral enhancement scales associated with the two-parton twist-3 meson distribution amplitudes. It is found that the gluonic contribution is negligible in the form factors, and reaches few percents in the ones. Its impact on the accommodation of the measured branching ratios in the perturbative QCD and QCD-improved factorization approaches is elaborated.

13 pages, 9 figures, a missing overall coefficient was included into the gluonic contribution. The numerical results were revised accordingly

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