We report cross sections for the process γ γ PP at center-of-mass energies W from 2.0 to 2.8 GeV. These results have been extracted from measurements of e+e e + e -pp at an overall center-of-mass energy of 29 GeV, using the TPC/Two-Gamma facility at the SLAC storage ring PEP. Cross sections for the untagged mode (both photons nearly real] arc shown to lie wsll above QCD predictions. Results are also presented for the single-tagged mode [one photon in the range 0.16 < Q2 < 1.6 (GeV/c)2).
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)