Sources of Radial-Flow Fluctuations in the Quark-Gluon Plasma

The differential radial flow fluctuation v0(pT) has emerged as a new probe of the quark-gluon plasma. However, its characteristic rise-and-fall pattern with pT, resembling anisotropic flow, remains unexplained. I introduce a momentum rescaling framework that factorizes v0(pT) into kinematic and dynamical components: v0(pT)/v0=-[dln⟨n(pT)⟩/dlnpT+1]×g(pT). The first factor, determined by spectral shape, generates the rise-and-fall pattern as the spectra transition from exponential to power-law behavior. The dynamical component g(pT) isolates pT-dependent dynamics: <1 signals suppressed fluctuations, >1 indicates enhancement. Analysis of LHC data reveals g(pT) deviates from unity by 20%–40% in central collisions. Predictions for RHIC show that spectral shape alone generates the rise-and-fall baseline pattern with substantial energy dependence. This framework enables tighter medium property constraints by separating kinematic from dynamical effects, with broad applications to anisotropic flow and higher-order radial flow fluctuations.