Measurement of π0π0 production in two-photon collisions
Abstract
The reaction e+e--->e+e-π0π0 has been analyzed using 97 pb-1 of data taken with the Crystal Ball detector at the DESY e-e+ storage ring DORIS II at beam energies around 5.3 GeV. For the first time we have measured the cross section for γγ-->π0π0 for π0π0 invariant masses ranging from threshold to about 2 GeV. We measure an approximately flat cross section of about 10 nb for W=m0ππ0<0.8 GeV, which is below 0.6 GeV, in good agreement with a theoretical prediction based on an unitarized Born-term model. At higher invariant masses we observe formation of the f2(1270) resonance and a hint of the f0(975). We deduce the following two-photon widths: Γγγ(f2(1270))=3.19+/-0.16+/-0.290.28 keV and Γγγ(f0(975))<0.53 keV at 90% C.L. The decay-angular distributions show the π0π0 system to be dominantly spin 0 for W<0.7 GeV and spin 2, helicity 2 in the f2(1270) region, with helicity 0 contributing at most 22% (90% C.L.).
- Publication:
-
Physical Review D
- Pub Date:
- June 1990
- DOI:
- 10.1103/PhysRevD.41.3324
- Bibcode:
- 1990PhRvD..41.3324M