Why heavy and light quarks radiate energy with similar rates

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.

Comments: Based on the talk given by B.K. at the Workshop on Critical Examination of RHIC Paradigms, Austin, April 14-17, 2010