The contribution of the four-parton final states to γ*γ*→ hadrons

In the analysis of the total cross section for the γ*γ*→ hadrons process, we include the four parton final states, which are part of the (αs2) corrections. The four-parton final states contain the diagrams with gluon exchange in the crossed channel, which constitute the leading order of the BFKL resummation. We show that the diagrams with gluon exchange in the crossed channel play an important role in the large Y region, however their contribution to the cross section must be evaluated exactly. In fact, the high-energy limit, which constitutes the kinematic framework of the BFKL resummation, is not sufficiently accurate at LEP2 energies. The inclusion of the diagrams with gluon exchange in the crossed channel reduces the discrepancy between the theory and the LEP2 data collected by the L3 Collaboration, but the data still lie above the theory, even allowing for a large scale uncertainty in the theory. Thus, in order to describe accurately the data for γ*γ*→ hadrons in the large Y region, corrections of an order higher than (αs2) seem to be necessary.