Speaker
Description
A central challenge in jet-quenching phenomenology is consistently modeling the transition from high-virtuality, vacuum-like parton showers to the transport of hard partons through the quark-gluon plasma (QGP). In multistage frameworks, this boundary is commonly parametrized by a matching scale $Q_0$, which has traditionally been constrained only indirectly through inclusive hadron and jet yield observables. Whether this transition can be directly isolated—and whether a sharp scale separation adequately captures in-medium shower dynamics—remains a major open question.In this talk, I will demonstrate that the jet Energy-Energy Correlator (EEC) acts as a remarkably sensitive probe of the vacuum-to-medium transition by directly resolving parton shower dynamics across angular and virtuality scales. Using the LIDO parton transport model, we systematically study medium-modified EEC distributions while varying $Q_0$, the jet-medium coupling strength, and the soft-particle cutoff governing medium response. We find that the EEC exhibits a strong, distinct dependence on $Q_0$, whereas variations in the coupling strength and soft-particle cutoff yield noticeably smaller effects. These findings establish the EEC as a unique observable for pinning down the onset of QGP interactions and testing the validity of multistage descriptions. Finally, I will present predictions for EEC distributions and their $p$-$p$ baseline ratios across system sizes—including $p$-Pb, O-O, and Pb-Pb collisions—highlighting key opportunities for current and future experimental tests.
