The reaction e+e-e+e-00 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 00 for 00 mvariant masses ranging from threshold to about 2 GeV. We measure an approximately flat cross section of about 10 nb for W=m00<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: f2(1270))=3.19±0.16±0.280.29 keV and (f0(975))<0.53 keV at 90% C.L. The decay-angular distributions show the 00 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.).
ASJC Scopus subject areas
- Nuclear and High Energy Physics