Theoretical description of the total $\gamma^*\gamma^*$ cross-section and its confrontation with the LEP data on doubly tagged $e^+e^-$ events

Abstract.

We perform a detailed analysis of the total inelastic cross-section for $\gamma^*\gamma^*$ collisions. Different contributions coming from the quark box diagram, reggeons, the soft and hard pomeron are included. The QCD pomeron contribution contains a dominant part of subleading effects which reduces its intercept and delays the onset of the asymptotic pomeron to high energies. Estimates of the cross-section for doubly-tagged $e^+e^- \to e^+e^- hadrons$ events are presented and compared with the existing LEP data. Good agreement between the theoretical results and the experimental data is found. We also comment on the extraction of the BFKL pomeron intercept from the available LEP measurements.