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Particles and Fields

Eur. Phys. J. C 22, 439-450 (2001)
DOI: 10.1007/s100520100830

The annihilation of virtual photons into pseudoscalar mesons

M. Diehl1, P. Kroll2 and C. Vogt2

1  Deutsches Elektronen-Synchroton DESY, 22603 Hamburg, Germany
2  Fachbereich Physik, Universität Wuppertal, 42097 Wuppertal, Germany

(Received: 30 August 2001 / Published online: 23 November 2001 - © Springer-Verlag / Società Italiana di Fisica 2001 )

We investigate the possibility to constrain the pion distribution amplitude from the $\gamma^* \gamma^* \to\pi$ transition. For a surprisingly large range in the two photon virtualities we find that the transition form factor is essentially independent of the distribution amplitude. This in turn entails a parameter-free prediction of QCD. The $\gamma^* \gamma^* \to\eta,\,
\eta'$ form factors are also briefly discussed. We estimate that experimental studies might be feasible at the existing e+e- experiments BaBar, Belle, and CLEO.

© Società Italiana di Fisica, Springer-Verlag 2001