Measurement of neutral pion pair production in two-photon collisions

Understand

The differential cross section of the process gamma gamma -> pi^0 pi^0 has been measured in the kinematical range 0.6 GeV < W < 4.0 GeV and |cos theta*|<0.8 in energy and pion scattering angle, respectively, in the gamma gamma center-of-mass system.

• We find at least four resonant structures including a peak from f_0(980).
• In addition, there is evidence for chi_{c0} production.
• We also make a preliminary discussion of the angular dependence and cross section ratio to gamma gamma -> pi^+ pi^-.