UC Berkeley

This study presents a systematic investigation of the transverse-momentum differential radial flow fluctuations observable in relativistic heavy-ion collisions at top Relativistic Heavy Ion Collider ( GeV) and Large Hadron Collider ( and 5.02 TeV) energies. Using a multistage hydrodynamic model, this study assesses the sensitivity of to a wide range of physical effects, including bulk and shear viscosities, off-equilibrium corrections at particlization, the presence of a hadronic afterburner, and the nucleon size in the initial conditions. By employing complementary rescaling strategies, this study demonstrates how different physical effects leave distinct imprints on the shape of . A combined double-rescaling of versus reveals a universality across a wide range of energies and model assumptions in the low- regime, a robust signature of collective behavior. This allows us to disentangle the universal dynamics of the bulk medium from model-specific features that emerge at higher . These results establish as a powerful and complementary observable for constraining quark-gluon plasma transport properties and initial-state granularity, offering a unique probe of the created QCD medium.