A phenomenological study of BFKL evolution

TL;DR

This paper investigates BFKL evolution in QCD through phenomenological fits to HERA data, explores its applicability at LEP and future colliders, and examines the impact of higher order corrections on BFKL predictions.

Contribution

It provides a unified BFKL-based description of nucleon structure functions and diffractive processes, and assesses the effects of next-to-leading order corrections on BFKL observables.

Findings

Successful fit of H1 data with a four-parameter model

Effective testing of BFKL dynamics at LEP and future colliders

Large higher order corrections reduce BFKL cross-section sensitivity

Abstract

The QCD dipole picture allows to build an unified theoretical description -based on BFKL dynamics- of the total and diffractive nucleon structure functions measured at HERA. We use a four parameter fit to describe the 1994 H1 proton structure function $F_{2}$ data in the low x, moderate $Q^{2}$ range. The diffractive dissociation processes are discussed within the same framework, and a 6 parameter fit of the 1994 H1 diffractive structure function data is performed. The BFKL dynamics can also be successfully tested at the $e^+e^-$ collider LEP and a future high energy linear collider. The total $\gamma^*\gamma^*$ cross-section is calculated in the Leading Order QCD dipole picture of BFKL dynamics, and compared with the one from 2-gluon exchange. Next to Leading order corrections to the BFKL evolution have been determined phenomenologically, and are found to give very large corrections to the BFKL cross-section, leading to a reduced sensitivity for observing BFKL effects. The Y dependence of the cross-section remains a powerful tool to increase the ratio between the BFKL and the 2-gluon cross-sections and is more sensitive to BFKL effects, even in the presence of large higher order corrections.