Study of pT-differential radial flow in blast-wave model

The transverse momentum-differential radial flow observable v₀(pT), recently proposed and measured by the ATLAS and ALICE collaborations, provides a novel tool to probe radial expansion dynamics in high-energy heavy-ion collisions. In this work, we conduct a detailed study of v₀(pT) using a blast-wave model that incorporates hydrodynamic-like expansion and thermal emission. We introduce event-by-event fluctuations in the transverse expansion velocity and kinetic freeze-out temperature using Gaussian probability distributions. Our results show that increasing the mean expansion velocity leads to a clear mass ordering in v₀(pT), while fluctuations in both expansion velocity and freeze-out temperature significantly enhance the magnitude of v₀(pT), particularly at higher pT. We fit blast-wave model calculations for identified hadrons (π, K, and p) to recent ALICE data from Pb--Pb collisions at √sNN = 5.02 TeV using a Bayesian parameter estimation framework. The extracted mean transverse expansion velocity decreases, while the kinetic freeze-out temperature increases, from central to peripheral collisions. Additionally, the freeze-out temperatures inferred from v₀(pT) are systematically higher than those obtained from conventional pT-spectra fits, likely due to the reduced sensitivity of v₀(pT) to resonance decay contributions.