Resummation in nonlinear equation for high energy factorizable gluon density and its extension to include coherence

TL;DR

This paper develops a resummed evolution equation for high energy gluon densities in QCD, extended to include color coherence effects, enabling better predictions for high transverse momentum processes in p-Pb collisions.

Contribution

It introduces a resummed form of the gluon density evolution equation and extends it to incorporate color coherence effects, improving the modeling of high energy scattering processes.

Findings

Resummed evolution equation for gluon densities formulated.

Extended equation includes color coherence effects.

Framework applicable to predictions of high p_t final states.

Abstract

Motivated by forthcoming p-Pb experiments at Large Hadron Collider which require both knowledge of gluon densities accounting for saturation and for processes at a wide range of $p_t$ we study basic momentum space evolution equations of high energy QCD factorization. Solutions of those equations might be used to form a set of gluon densities to calculate observables in generalized high energy factorization. Moreover in order to provide a framework for predictions for exclusive final states in p-Pb scattering with high $p_t$ we rewrite the equation for the high energy factorizable gluon density in a resummed form, similarly to what has been done in \cite{Kutak:2011fu} for the BK equation. The resummed equation is then extended to account for colour coherence. This introduces an external scale to the evolution of the gluon density, and therefore makes it applicable in studies of final states.