Distinctive features of hadronizing heavy quarks

TL;DR

This paper explains how the dead-cone effect influences heavy quark fragmentation, resulting in a peaked fragmentation function and short fragmentation lengths, indicating a predominantly perturbative process.

Contribution

It demonstrates that heavy quark fragmentation is mainly perturbative and characterizes the space-time development of heavy quark jets considering the dead-cone effect.

Findings

Heavy quarks radiate a small fraction of their energy due to the dead-cone effect.

The heavy quark fragmentation function peaks at large fractional momenta z.

Fragmentation lengths are much shorter than the confinement radius.

Abstract

The color field of a quark, stripped off in a hard reaction, is regenerated via gluon radiation. The space-time development of a jet is controlled by the coherence time of gluon radiation, which for heavy quarks is subject to the dead-cone effect, suppressing gluons with small transverse momenta. As a result, heavy quarks can radiate only a small fraction of the initial energy. This explains the peculiar shape of the measured heavy quark fragmentation function, which strongly peaks at large fractional momenta z. The fragmentation length distribution, related to the fragmentation function in a model independent way, turns out to be concentrated at distances much shorter than the confinement radius. This implies that the mechanisms of heavy quark fragmentation is pure perturbative.