Dynamical correlations across momentum scales in the Quark-Gluon Plasma

TL;DR

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Contribution

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Abstract

Experimental probes of the Quark-Gluon Plasma (QGP) generated in heavy-ion collisions span a broad range in momentum scale: low transverse momentum (low $p_T$) measurements probe collective dynamics, while high $p_T$ measurements probe the response to QGP excitation by jets (jet quenching). However, the dynamical interplay between QGP collective dynamics and jet quenching is currently poorly understood. We present a new framework for exploring dynamical correlations across momentum scales in heavy-ion collisions, based on the $p_T$-differential radial-flow observable $v_0(p_T)$. Measured $v_0(p_T)$ phenomenology is traced to the evolution in strength and coherence of distinct underlying fluctuation modes. We then propose new experimental observables to quantify this evolution. The eigenvalue ratio $\lambda_2/\lambda_1$ of the reference-aligned covariance matrix $V_0$ is shown to measure the effective fluctuation rank, while the $p_T$-dependence of the corresponding eigenvectors maps the evolution from a single coherent soft mode to multi-mode dynamics including coalescence and jet quenching. These observables map the soft-mid-hard correlation structure and provide a unified description of the collective-to-partonic transition in the QGP.