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

Abstract

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}^{+}$${e}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$${\ensuremath{\gamma}}^{\mathrm{*}}$${\ensuremath{\gamma}}^{\mathrm{*}}$\ensuremath{\rightarrow}e $^{+}e^{\mathrm{\ensuremath{-}}}$+hadrons with both scattered ${e}^{+}$ and ${e}^{\mathrm{\ensuremath{-}}}$ detected. Each photon's four-momentum squared, ${q}^{2}$, ranges from -0.1 to -1.6 ${\mathrm{GeV}}^{2}$. Dependence upon ${q}^{2}$ agrees with a generalized vector-meson-dominance model. The total cross section shows little W dependence, averaging 125 nb at ${q}_{1}^{2}$=${q}_{2}^{2}$=-0.3. Photon helicity interference terms are determined.