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arXiv · 2610.27182

Jets as differential probes of hot QCD matter

João M. Silva
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Abstract

Ultra-relativistic heavy-ion collisions create short-lived droplets of deconfined, hot QCD matter whose evolution connects far-from-equilibrium early dynamics to the hydrodynamic quark-gluon plasma. High-energy jets, produced in early hard scatterings and modified by this evolving medium, provide multi-scale probes of its microscopic properties. This thesis develops perturbative QCD tools to extract information about hot QCD matter from its imprint on differential jet substructure observables. Our framework is the BDMPS-Z description of high-energy partons propagating through stochastic colour fields. We first study anisotropic QCD matter by replacing the usual scalar broadening parameter with direction-dependent transverse momentum broadening. This relates anisotropic corrections to medium-induced splittings to spin information and azimuthal patterns in final-state energy flow. Energy correlators are then used as observables sensitive to these effects, including heavy-flavour EECs, azimuthally differential EECs and clover projections designed to isolate leading anisotropy-induced harmonics. We also examine how energy loss affects the interpretation of jet substructure modifications. Quantile matching defines reconstructed energy loss as a population-level shift between vacuum and medium-modified jet spectra. We further develop energy-loss functions, which encode the distribution of energy retained by jet-originated hadrons, and show how their moments enter multi-point projected energy correlators. Finally, we go beyond single $1\to2$ medium-induced splittings by studying spin-induced correlations between successive emissions and higher-point energy correlators including contributions from medium response. The results show that differential jet substructure can probe directional properties of QCD matter and multi-point dynamics of jets propagating through it.

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BibTeXRIS

João M. Silva. 2026-10-19. Jets as differential probes of hot QCD matter. https://arxiv.org/abs/2610.27182

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