Messung des hadronischen Wirkungsquerschnitts doppelt markierter 2-Photon Ereignisse

The interaction of virtual photons has been investigated using double tagged γ * γ * -events with hadronic final states, taken by the ALEPH experiment at e + e - center-of-mass energies √S ee =189 - 208 GeV. The measured cross section is compared to the PYTHIA and PHOT02 Monte Carlo Model, a NLO QCD calculation and BFKL calculations. The NLO QCD prediction is largely consistent with the data. The LO BFKL predictions are ruled out by the data.