https://doi.org/10.1140/epjc/s10052-012-1964-7
Regular Article - Theoretical Physics
Novel insights into the γγ ∗→π 0 transition form factor
1
Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, P.R. China
2
Theoretical Physics Center for Science Facilities, CAS, Beijing, 100049, China
* e-mail: guozk@ihep.ac.cn
Received:
16
February
2012
Published online:
11
April
2012
BaBar’s observation of significant deviations of the pion transition form factor (TFF) from the asymptotic expectation with Q
2>9 GeV2 has brought about a serious crisis to the fundamental picture established for such a simple 
system by perturbative QCD, i.e. the dominance of collinear factorization at high momentum transfers for the pion TFF. We show that non-factorizable contributions due to open flavors in γγ
∗→π
0 could be an important source that contaminates the pQCD asymptotic limit and causes such deviations with Q
2>9 GeV2. Within an effective Lagrangian approach, the non-factorizable amplitudes can be related to intermediate hadron loops, i.e. K
(∗) and D
(∗) etc., and their corrections to the π
0 and η TFFs can be estimated.
© Springer-Verlag / Società Italiana di Fisica, 2012
