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The photon-pion transition form factor for virtual photons

M. Diehl·P. Kroll·C. Vogt
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Abstract

We discuss the photon to meson transition form factor for virtual photons, which can be measured in e+ e- collisions. We demonstrate that this form factor is independent of the shape of the meson distribution amplitude over a wide kinematical range. This leads to a parameter-free prediction of perturbative QCD to leading twist accuracy, which has a status comparable to the famous leading-twist prediction of the cross section ratio R.

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M. Diehl, P. Kroll, C. Vogt. 2001-11-13. The photon-pion transition form factor for virtual photons. https://arxiv.org/abs/hep-ph/0105342

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