Decoupling of the leading contribution in the discrete BFKL Analysis of High-Precision HERA Data

TL;DR

This paper investigates the discrete eigenvalues of the NLO BFKL equation and demonstrates that a set of eigenfunctions effectively describes high-precision HERA data, revealing a decoupling of the first eigenfunction and suggesting an additional saturated ground state.

Contribution

It introduces a detailed analysis of the discrete eigenvalue solution in NLO BFKL and uncovers the decoupling of the leading eigenfunction, proposing a new perspective on the soft pomeron.

Findings

Eigenfunctions with positive eigenvalues describe HERA data well

The first eigenfunction decouples from the proton

Evidence for an additional saturated ground state

Abstract

We analyse, in NLO, the physical properties of the discrete eigenvalue solution for the BFKL equation. We show that a set of eigenfunctions with positive eigenvalues, \omega, together with a small contribution from a continuum of eigenfunctions with negative \omega, provide an excellent description of high-precision HERA F_2 data in the region, x<0.001, Q^2 > 6 GeV^2. The phases of the eigenfunctions can be obtained from a simple parametrisation of the pomeron spectrum, which has a natural motivation within BFKL. The data analysis shows that the first eigenfunction decouples completely or almost completely from the proton. This suggests that there exist an additional ground state, which is naturally saturated and may have the properties of the soft pomeron.