High-statistics study of neutral-pion pair production in two-photon collisions
Abstract
The differential cross sections for the process γγ→π0π0 have been measured in the kinematic range 0.6GeV<W<4.1GeV, |cosθ*|<0.8 in energy and pion scattering angle, respectively, in the γγ center-of-mass system. The results are based on a 223fb-1 data sample collected with the Belle detector at the KEKB e+e- collider. The differential cross sections are fitted in the energy region 1.7GeV<W<2.5GeV to confirm the two-photon production of two pions in the G wave. In the higher-energy region, we observe production of the χc0 charmonium state and obtain the product of its two-photon decay width and branching fraction to π0π0. 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 π+π- channel, and in addition we find that the cross section ratio, σ(π0π0)/σ(π+π-), is 0.32±0.03±0.05 on average in the 3.1-4.1 GeV region.
- Publication:
-
Physical Review D
- Pub Date:
- March 2009
- DOI:
- 10.1103/PhysRevD.79.052009
- arXiv:
- arXiv:0903.3697
- Bibcode:
- 2009PhRvD..79e2009U
- Keywords:
-
- 13.20.Gd;
- 13.60.Le;
- 13.66.Bc;
- 14.40.Cs;
- Decays of J/psi Upsilon and other quarkonia;
- Meson production;
- Hadron production in e<sup>-</sup>e<sup>+</sup> interactions;
- Other mesons with S=C=0 mass<
- 2.5 GeV;
- High Energy Physics - Experiment
- E-Print:
- 22 pages, 10 figures