Measurement of the cross-section for the process $ee \to ee\gamma^{*}\gamma^{*} \to eeX$ at $\sqrt{S_{ee}}$ = 189 GeV

The hadronic structure of interactions of virtual photons ( gamma *) is investigated using the reaction ee to ee gamma * gamma * to eeX based on data taken by the OPAL experiment at square root (S/sub ee/) =189 GeV, where X represents the hadronic final state. The measured differential cross-sections are compared to the predictions of the leading order Monte Carlo model PHOJET1.10, and to a BFKL calculation. PHOJET1.10 describes the data reasonably well, whereas the cross-section prediction based on a BFKL calculation is significantly too high. (17 refs).