Heavy-Quark Dynamics from $D^{0}$-Meson Anisotropy-Response Scaling Violations

Abstract

A species-resolved anisotropy-response scaling framework is used to investigate heavy-quark dynamics through the elliptic ($v_2$) and triangular ($v_3$) azimuthal anisotropies of $D^0$ mesons. The independently constrained light-flavor response provides a direct null test: the transformed $D^0$ harmonics exhibit approximate inter-harmonic closure but remain systematically displaced from the kaon-anchored scaling function, revealing a charm scaling violation. The common response is recovered through a charm-specific attenuation rescaling, $k_c$, together with a small low-$p_T$ hadronic-rescattering correction, $ζ_{\rm hs}\simeq0.06$, while retaining the established light-flavor prescription. In Pb+Pb collisions at $\sqrt{s_{NN}}=5.02$~TeV, $k_c$ decreases from approximately $2.0$ in central and mid-central collisions to $1.27$ in the 30--50\% interval. For $D^0$ $v_2$, ultra-central p+Pb collisions at $\sqrt{s_{NN}}=8.16$~TeV require $k_c\simeq1.5$, whereas Au+Au collisions at $\sqrt{s_{NN}}=200$~GeV are consistent with $k_c\simeq1$. The transition momentum exhibits a distinct system dependence: $D^0$ and light mesons show comparable $p_{T,\rm tr}\simeq4.5$--$5.0$~GeV/$c$ in Pb+Pb, consistent with the common large-system prescription also used in Au+Au, whereas p+Pb $D^0$ measurements are consistent with the lower light-meson scale of approximately $1.6$~GeV/$c$. These complementary constraints on attenuation strength and transition momentum provide a differential benchmark for heavy-quark transport and medium evolution.