Measurement of the total hadronic cross section in virtual photon-photon interactions

The total hadronic cross section for virtual photon-photon interactions is reported for center-of-mass energy, W, between 2 and 20 GeV. The data were obtained via the process e+e-→e+e-γ*γ*→e e-++hadrons with both scattered e+ and e- detected. Each photon’s four-momentum squared, q2, ranges from -0.1 to -1.6 GeV2. Dependence upon q2 agrees with a generalized vector-meson-dominance model. The total cross section shows little W dependence, averaging 125 nb at q12=q22=-0.3. Photon helicity interference terms are determined.