Probing the parton densities of virtual photons with the reaction gamma^*gamma->jets at LEP

TL;DR

This paper provides a next-to-leading order calculation of jet production in virtual photon collisions at LEP, comparing direct and resolved photon approaches to distinguish parton densities.

Contribution

It introduces a detailed NLO calculation for virtual photon-induced jet production, analyzing the impact of different parton density parametrizations.

Findings

Perturbative stability varies between direct and resolved photon approaches.

Predictions suggest measurable differences in jet cross sections for different virtual photon parton densities.

Results are applicable to LEP2 conditions for experimental validation.

Abstract

We present a next-to-leading order calculation of jet production in gamma^*gamma collisions from e+e- scattering in a region where the virtuality Q^2 of the probing virtual photon is small compared to the transverse jet energy. The calculation is based on the phase-space slicing method. The initial state singularity of the virtual photon is factorized into the structure function of the virtual photon, using the MS-bar factorization scheme for virtual photons. Numerical results are presented for LEP2 conditions. The perturbative stability of the pure direct virtual photon approach is compared to that of including resolved virtual photons in different regions of Q^2. We make predictions for cross sections which suggest that different parametrizations of virtual photon parton densities should be distinguishable by measurements of jet cross sections at LEP.