A Measurement of the Total Hadronic Cross Section in Tagged 77 Reactions *

We present a measurement of the total cross section for yy + hadrons, with one photon quasi-real and the other a spacelike photon of mass-squared-Q2. Results are presented as a function of Q2 and the yy center-of-mass energy W, with the Q2 range extending from 0.2 GeV2 to 60 GeV2, and W in the range from 2 to 10 GeV. The data were taken with the TPC/T wo-Gamma facility at the SLAC eSe-storage ring PEP, which was operated at a beam energy of 14.5 GeV. The cross section exhibits a gentle fall-off with increasing W. Its Q2-dependence is shown to be well-described by an incoherent sum of vector-meson and point-like scattering over most of the observed W range. Agreement at high Q2 is improved if a minimum pT cutoff (motivated by &CD) is imposed on the point-like contribution.