The contribution of medium-modified color flow to jet quenching

TL;DR

This paper investigates how medium-modified color flow in parton showers affects jet quenching phenomena in heavy ion collisions, revealing that color decoherence influences hadronization and jet fragmentation patterns.

Contribution

It introduces a color-differential calculation of medium-induced gluon radiation and analyzes the impact of medium-modified color flow on jet fragmentation using the Lund model.

Findings

Medium interactions cause color decoherence of gluons in jets.

Color decoherence affects the distribution of soft and leading hadrons.

Medium modifications can enhance soft hadron production and suppress leading hadrons.

Abstract

Multiple interactions between parton showers and the surrounding QCD matter are expected to underlie the strong medium-modifications of jet observables in ultra-relativistic heavy ion collisions at RHIC and at the LHC. Here, we note that such jet-medium interactions alter generically and characteristically the color correlations in the parton shower. We characterize these effects in a color-differential calculation of the medium-induced gluon radiation spectrum to first and second order in opacity. By interfacing simple branching histories of medium-modified color flow with the Lund hadronization model, we analyze how the medium modification of color correlations can affect the distribution of hadronic fragments in jets. Importantly, we observe that jet-medium interactions give rise to the medium-induced color decoherence of gluons from the parton shower. Since hadronization respects color flow and since each color singlet in a parton shower is hadronized separately, this medium-induced color decoherence leaves characteristic signatures in the jet fragmentation pattern. In particular, it can contribute to the quenching of leading hadron spectra. Moreover, it can increase strongly the yield of soft hadronic fragments from a jet, while the distribution of more energetic hadrons follows naturally the shape of a vacuum-like fragmentation pattern of lower total energy.