Seminar in Hadronic Physics

Exploring jet transport coefficients in the quark-gluon plasma

Amit Kumar

McGill University

The modifications of hard jets play an essential role as multi-scale probes of the properties of the Quark-Gluon Plasma (QGP) produced in high-energy heavy-ion collisions. In this talk, we explore the interplay between the soft and hard scales involved in the modification of jet partons as they propagate through the QGP. We present an attempt to probe the underlying structure of the QGP at high resolution, based on the extracted jet transport coefficient $\hat{q}$. Our results strongly suggest that the enhancement in the interaction strength $\hat{q}$/T³ at RHIC relative to LHC collision energies is not caused by the temperature dependence of $\hat{q}$/T³, but rather by the scale dependence of $\hat{q}$. We have also constructed a framework to study the non-perturbative component in the parton energy-loss using lattice QCD. We shall present the first lattice determination of $\hat{q}$ for the pure gluon plasma and a 2+1 flavor QCD plasma. In the end, we also demonstrate the importance of multi-stage energy loss using JETSCAPE framework. We highlight the role played by the “recoil” partons and scale-dependent $\hat{q}$ in the simultaneous description of the leading hadron and jet observables.