CCFM Evolution with Unitarity Corrections

TL;DR

This paper extends the CCFM evolution framework by incorporating unitarity corrections to model saturation effects, revealing that saturation leads to similar predictions for gluon densities as BFKL evolution, with implications for phenomenology.

Contribution

It introduces a detailed implementation of saturation effects in CCFM evolution, compares it with BFKL, and proposes non-leading modifications for better phenomenological modeling.

Findings

CCFM and BFKL give similar predictions with saturation effects

Saturation momentum's energy dependence is characterized

Non-leading modifications of CCFM are proposed

Abstract

We considerably extend our previous analysis of the implementation of an absorptive boundary condition, which mimics saturation effects, on the linear CCFM evolution. We present detailed results for the evolution of the unintegrated gluon density in the presence of saturation and extract the energy dependence of the emerging saturation momentum. We show that CCFM and BFKL evolution lead to almost identical predictions after including the effects of gluon saturation and of the running of the coupling. We moreover elucidate several important and subtle aspects of the CCFM formalism, such as its relation to BFKL, the structure of the angular ordered cascade, and the derivation of more inclusive versions of CCFM. We also propose non--leading modifications of the standard CCFM evolution which may play an important role for phenomenological studies.