Abstract
The differential cross sections for the process have been measured in the kinematic range , in energy and pion scattering angle, respectively, in the center-of-mass system. The results are based on a data sample collected with the Belle detector at the KEKB collider. The differential cross sections are fitted in the energy region to confirm the two-photon production of two pions in the wave. In the higher-energy region, we observe production of the charmonium state and obtain the product of its two-photon decay width and branching fraction to . We also compare the observed angular dependence and ratios of cross sections for neutral-pion and charged-pion pair production to QCD models. The energy and angular dependence above 3.1 GeV are compatible with those measured in the channel, and in addition we find that the cross section ratio, , is on average in the 3.1–4.1 GeV region.
3 More- Received 22 January 2009
DOI:https://doi.org/10.1103/PhysRevD.79.052009
©2009 American Physical Society