Quenching jets increases their flavor

TL;DR

This paper challenges the common belief that quenched jets in a Quark-Gluon Plasma retain their original flavor composition, showing that they can become predominantly fermionic at intermediate momenta due to flavor conversion.

Contribution

It demonstrates, through perturbative QCD calculations and simulations, that jet flavor composition changes significantly after quenching, especially at lower transverse momenta.

Findings

Quenched jets can become quark-dominated at intermediate $p_T$

Flavor conversion rates increase as $p_T$ decreases

The flavor change relates to observed baryon enhancement

Abstract

The widespread notion that jets quenched in a Quark-Gluon-Plasma (QGP) are similar in their parton flavor composition to jets in vacuum is critically examined. We demonstrate that while the soft to semi-hard [low to intermediate transverse momentum ($p_T$)] sector of vacuum jets are predominantly bosonic i.e., composed of gluons, \emph{sufficiently} quenched jets can have an intermediate momentum sector that is predominantly fermionic, dominated by quarks and antiquarks. We demonstrate, using leading order perturbative QCD processes, that the rate of flavor conversion from a gluon traversing the QGP as part of a jet, to a quark or antiquark, versus the reverse process, grows steadily with falling $p_T$. Simple diagrammatic estimates are followed by a variety of realistic simulations in static media. The relation of this increase in flavor to the observed baryon enhancement at intermediate $p_T$ is studied in a fully realistic simulation.