Flavoring the Quark-Gluon Plasma with Charm

TL;DR

This paper shows that adding a small amount of heavy charm quarks to the Quark-Gluon Plasma reduces its speed of sound, providing a new way to probe microscopic dynamics through heavy ion collision experiments.

Contribution

It introduces the concept that heavy flavor admixture affects the QGP's hydrodynamic properties, offering a novel experimental probe.

Findings

Heavy quark admixture lowers the speed of sound in QGP.

The effect is sensitive to microscopic theory details.

Potential measurement via charm quark count and flow observables.

Abstract

We demonstrate that a Quark-Gluon Plasma (QGP) with a dilute admixture of heavy quarks has, in general, a lower speed of sound than a "pure" QGP without effects from heavy flavors. The change in the speed of sound is sensitive to the details of the theory, making the hydrodynamic response to "flavoring" a sensitive probe of the underlying microscopic dynamics. We suggest that this effect may be measured in ultrarelativistic heavy ion collisions by relating the event-by-event number of charm quarks to flow observables such as the average transverse momentum.