Azimuthal Anisotropy Scaling Functions for Identified Particle and Anti-Particle Species across Beam Energies: Insights into Baryon Junction Effects

TL;DR

This study constructs species-resolved azimuthal anisotropy scaling functions across various collision energies to investigate baryon transport, medium response, and critical dynamics in heavy-ion collisions.

Contribution

It introduces a data-driven framework that reveals universal scaling behaviors and baryon-number effects, providing new insights into baryon stopping and QGP properties.

Findings

Meson and baryon anisotropies collapse onto common scaling curves.

The attenuation scale $k_\beta$ shows a non-monotonic energy dependence.

Baryon-antibaryon separation increases at lower collision energies.

Abstract

Azimuthal anisotropy scaling functions are constructed from species-resolved anisotropy measurements in Pb+Pb ($\sqrt{s_{NN}}=2.76$, $5.02$ TeV) and Au+Au ($\sqrt{s_{NN}}=7.7$-$200$~GeV) collisions to probe baryon transport and medium response at finite baryon chemical potential ($\mu_B$). Within this data-driven framework, meson and baryon anisotropies spanning the collective-flow and quenching regimes collapse onto common scaling curves, enabling quantitative separation of viscous attenuation, radial flow, and hadronic re-scattering. The attenuation scale $k_\beta$ exhibits a non-monotonic beam-energy dependence, coincident with the low-energy rise of hadronic re-scattering, consistent with a temperature-dependent specific shear viscosity featuring a near-minimum near the QCD critical region. A charge-odd baryon-antibaryon separation in the effective radial-flow response is negligible at LHC energies but grows toward lower $\sqrt{s_{NN}}$. This species-uniform, baryon-number-scaling separation across $p,\Lambda,\Xi,\Omega,$ and $d$ disfavors a purely hadronic origin and supports junction-driven net-baryon transport at finite $\mu_B$, enhancing the experimental visibility of critical dynamics in finite, rapidly evolving systems. Together, these results establish species-resolved scaling functions as a compact and robust tool for constraining baryon stopping, medium opacity, and QGP transport properties.