Speaker
Description
Jet quenching plays an important role as a hard probe to study properties of the quark–gluon plasma (QGP) in heavy-ion collisions at both the relativistic heavy-ion collider and the large hadron collider. During their travel in the QGP, high energy partons lose their energy mainly through splitting processes like bremsstrahlung and pair production, induced by elastic scatterings with the medium. When repeated, a shower of lower energy particles is produced. In the high energy limit, these splitting processes are coherent over large distances and the underlying elastic scatterings can no longer be treated as quantum mechanically independent, leading to a suppression of the splitting rate known as the Landau-Pomeranchuk-Migdal effect. We studied whether high-energy parton showers inside a QGP can be treated as a sequence of individual splitting processes, or whether there is significant quantum overlap between where one splitting ends and the next begins. Previously, the overlap of splitting rates has been calculated at leading-log order, and it was found that such corrections are large but can be absorbed into an effective value of the jet-quenching parameter $\hat{q}$ that characterizes the medium. Going beyond leading logarithms (in the simplest theoretical situation), we investigated a measure of overlap effects that cannot be absorbed into an effective value of $\hat{q}$. In this talk, I will summarize our recent results and comment on the implications of our study.
