Systematic study of azimuthal anisotropy in Cu + Cu and Au + Au collisions atsNN=62.4and 200 GeV

We have studied the dependence of azimuthal anisotropy ${v}_{2}$ for inclusive and identified charged hadrons in $\mathrm{Au}+\mathrm{Au}$ and $\mathrm{Cu}+\mathrm{Cu}$ collisions on collision energy, species, and centrality. The values of ${v}_{2}$ as a function of transverse momentum ${p}_{T}$ and centrality in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{{s}_{{}_{\mathit{NN}}}}=200$ and 62.4 GeV are the same within uncertainties. However, in $\mathrm{Cu}+\mathrm{Cu}$ collisions we observe a decrease in ${v}_{2}$ values as the collision energy is reduced from 200 to 62.4 GeV. The decrease is larger in the more peripheral collisions. By examining both $\mathrm{Au}+\mathrm{Au}$ and $\mathrm{Cu}+\mathrm{Cu}$ collisions we find that ${v}_{2}$ depends both on eccentricity and the number of participants, ${N}_{\mathrm{part}}$. We observe that ${v}_{2}$ divided by eccentricity ($\ensuremath{\varepsilon}$) monotonically increases with ${N}_{\mathrm{part}}$ and scales as ${N}_{\mathrm{part}}^{1/3}$. The $\mathrm{Cu}+\mathrm{Cu}$ data at 62.4 GeV falls below the other scaled ${v}_{2}$ data. For identified hadrons, ${v}_{2}$ divided by the number of constituent quarks ${n}_{q}$ is independent of hadron species as a function of transverse kinetic energy $K{E}_{T}={m}_{T}\ensuremath{-}m$ between $0.1lK{E}_{T}/{n}_{q}l1$ GeV. Combining all of the above scaling and normalizations, we observe a near-universal scaling, with the exception of the $\mathrm{Cu}+\mathrm{Cu}$ data at 62.4 GeV, of ${v}_{2}/({n}_{q}\ifmmode\cdot\else\textperiodcentered\fi{}\ensuremath{\varepsilon}\ifmmode\cdot\else\textperiodcentered\fi{}{N}_{\mathrm{part}}^{1/3})$ vs $K{E}_{T}/{n}_{q}$ for all measured particles.