Azimuthal dependence of two-particle transverse momentum current correlations

Two-particle transverse momentum correlation functions are a powerful technique for understanding the dynamics of relativistic heavy-ion collisions. Among these, correlator $G_{2}\left(\Delta\eta,\Delta\varphi\right)$ is particular interest its potential sensitivity to shear viscosity per unit entropy density $\eta/s$ quark-gluon plasma formed in We use UrQMD, AMPT, and EPOS models Au--Au at $\sqrt{s_{\rm NN}}$ = 200~GeV Pb--Pb 2760~GeV investigate long range azimuthal dependence $G_{2}\left(\Delta\eta,\Delta\varphi\right)$, explore utility constrain based on charged particle correlations. find that three yield quantitatively distinct Fourier harmonics coefficients $a^{p_{\rm T}}_{\rm n}$. also observe these exhibit significant context AMPT model. These observations suggest exhaustive measurements $G_{2}\left(\Delta\varphi \right)$ with collision energy, system size, centrality, particular, offer distinguish between different theoretical their underlying assumptions. Exhaustive analyses obtained large small systems should be instrumental establishing new constraints precise extraction $\eta/s$.