Why heavy and light quarks radiate energy with similar rates

TL;DR

The paper explains why heavy and light quarks exhibit similar energy loss rates in high-energy collisions, challenging previous expectations based on the dead cone effect, by analyzing vacuum radiation and color field regeneration.

Contribution

It introduces a new understanding of vacuum radiation effects that cause heavy and light quarks to have comparable jet quenching, contrary to traditional dead cone predictions.

Findings

Vacuum radiation develops a wider dead cone for high virtuality quarks.

Gluon radiation is suppressed until the quark's color field is regenerated.

Heavy quarks like beauty are expected to be less suppressed at current energies.

Abstract

The dead cone effect has been expected to reduce the magnitude of energy loss and jet quenching for heavy flavors produced with large pT in heavy ion collisions. On the contrary, data from RHIC for open charm production demonstrate a flavor independent nuclear suppression. We show that vacuum radiation of a highly virtual quark produced at high pT with its color field stripped off, develops a much wider dead cone, which screens the one related to the quark mass. Lacking the field, gluons cannot be radiated within this cone until the color field is regenerated and the quark virtuality cools down to the scale of the order of the quark mass. However, this takes time longer than is essential for the observed jet quenching. This is the reason why the light and charm quark jets are quenched equally. Open beauty is expected to be suppressed much less within the pT range studied so far.