https://doi.org/10.1051/epjconf/20123705009
Measurement of γγ* → π0 transition form factor at Belle
KEK, Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization, Tsukuba, Japan
a e-mail: uehara@post.kek.jp
We report a measurement of the process γγ* → π0 with a 759 fb-1 data sample recorded with the Belle detector at the KEKB asymmetric-energy e+e- collider. The pion transition form factor, F(Q2), is measured for the kinematical region GeV2 ≲ Q2 ≲ 40 GeV2, where −Q2 is the invariant mass squared of a virtual photon. The measured values of Q2|F(Q2)| agree well with the previous measurements below Q2 ≃ 9 GeV2 but do not exhibit the rapid growth in the higher Q2 region seen in another recent measurement, which exceeds the asymptotic QCD expectation by as much as 50%.
© Owned by the authors, published by EDP Sciences, 2012
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
