QDC radioactive corrections to $\Boldsymbol{\Gamma^*\Gamma^*\To}$Hadrons

by Zoltan Trocsanyi (University of Debrecen )

Friday 2 Aug 2002, 14:00 → 15:00 Europe/Zurich

TH Auditorium (CERN)

We discuss an analysis of the total cross section for the $\gamma^*\gamma^*\to$ hadrons process including next-to-leading order corrections, as well as four-parton final states, which are part of the $\ord(\as^2)$ 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, but the latter still lie above the theory, even allowing for a large scale uncertainty in the theory.