Forward dijets in high-energy collisions: evolution of QCD n-point functions beyond the dipole approximation

TL;DR

This paper derives explicit evolution equations for higher n-point functions of Wilson lines in QCD, highlighting limitations of the Gaussian approximation and aiming to improve predictions of forward dijet correlations in high-energy collisions.

Contribution

It provides new evolution equations for 4- and 6-point Wilson line functions beyond the Gaussian approximation, enhancing QCD calculations for high-energy dijet phenomena.

Findings

Explicit evolution equations for 4- and 6-point functions derived.

Gaussian approximation misses many leading order contributions.

Potential to improve predictions of forward dijet angular correlations.

Abstract

Present knowledge of QCD n-point functions of Wilson lines at high energies is rather limited. In practical applications, it is therefore customary to factorize higher n-point functions into products of two-point functions (dipoles) which satisfy the BK evolution equation. We employ the JIMWLK formalism to derive explicit evolution equations for the 4- and 6-point functions of fundamental Wilson lines and show that if the Gaussian approximation is carried out before the rapidity evolution step is taken, then many leading order N_c contributions are missed. Our evolution equations could specifically be used to improve calculations of forward dijet angular correlations, recently measured by the STAR collaboration in deuteron-gold collisions at the RHIC collider. Forward dijets in proton-proton collisions at the LHC probe QCD evolution at even smaller light-cone momentum fractions. Such correlations may provide insight into genuine differences between the JIMWLK and BK approaches.