Species-Resolved Scaling of Azimuthal Anisotropy: Constraining Attenuation, Collective Expansion, and Hadronic Dynamics in Hydrodynamic Simulations

TL;DR

This study develops species-resolved azimuthal anisotropy scaling functions from hydrodynamic simulations of Pb+Pb collisions, revealing a universal scaling structure that constrains collective expansion and hadronic dynamics.

Contribution

It introduces a robust scaling framework for azimuthal anisotropy that quantitatively constrains hydrodynamic response and hadronic effects across energies and centralities.

Findings

Scaling functions collapse across particle species, momentum, and energy.

Quantitative agreement with experimental data is achieved using an energy-dependent attenuation baseline.

Scaling parameters reflect the interplay of collective expansion, system lifetime, and re-scattering.

Abstract

Species-resolved azimuthal anisotropy scaling functions are constructed from identified particle $v_2$ and $v_3$ obtained from event-by-event iEBE-VISHNU simulations for Pb+Pb collisions at $\sqrt{s_{NN}}=2.76$ and $5.02$~TeV. The scaling functions exhibit a robust collapse across transverse momentum, centrality, particle species, and beam energy, indicating a common and tightly constrained scaling structure. High scaling fidelity yields quantitative agreement with the data-defined reference through an energy-dependent attenuation baseline $\beta_0$ in central to mid-central collisions and a centrality-dependent modification of the effective attenuation in more peripheral collisions, with only a weak dependence on $\sqrt{s_{NN}}$. The multiplicity dependence of the extracted scaling parameters reflects the interplay of EOS-driven collective expansion, finite system lifetime, and hadronic re-scattering. These results demonstrate that the scaling framework provides a quantitative, constraint-driven probe of the hydrodynamic response, enabling the disentanglement and constraint of the coupled contributions to azimuthal anisotropy.