Do QGP Droplets Drive Anisotropy in Small Systems? Insights from RHIC and the LHC

Abstract

Azimuthal anisotropy scaling functions for identified mesons and baryons are analyzed in large (Pb+Pb at $\sqrt{s_{NN}} = 2.76$ and 5.02 TeV, Au+Au at $\sqrt{s_{NN}} = 200$ GeV), intermediate (Cu+Cu at $\sqrt{s_{NN}} = 200$~GeV), and small (p+Pb at $\sqrt{s_{NN}} = 5.02$ and 8.16 TeV, p+Au, d+Au, and $^3$He+Au at $\sqrt{s_{NN}} = 200$ GeV) collision systems. The scaling functions' fidelity supports a hydrodynamic-like origin for anisotropies in the flow-dominated regime. Central Pb+Pb, Au+Au, and Cu+Cu reflect QGP-driven expansion with strong radial flow and significant jet quenching, while peripheral Pb+Pb and Cu+Cu exhibit hadronic-dominated dynamics. In contrast, central RHIC small systems show hadronic-dominated behavior, with strong re-scattering, negligible radial flow, and suppressed jet quenching, following the hierarchy p+Au $>$ d+Au $>$ $^3$He+Au. At the LHC, ultra-central p+Pb collisions display enhanced radial flow, reduced re-scattering, and small but nonzero jet quenching. Scaling violations at high $p_T$ reflect partial suppression of partonic energy loss. These findings demonstrate that QGP-like behavior in small systems depends sensitively on both system size and beam energy, and establish the scaling framework as a robust diagnostic of collectivity and medium properties across diverse collision conditions.