Summary
=======

In summary, PHENIX has measured $\pi^0$ and $\eta$ invariant $p_T$-spectra and nuclear modification factors in asymmetric collisions of heavy ions, Cu$+$Au at $\sqrt{s_{_{NN}}}=200$ GeV in a wide $p_T$ range ($1(2)<p_T<20$ GeV/$c$) and for several centrality intervals. In the more central collisions the spectra are similar to those observed in . The asymptotic (high ) value of $\eta/{\mbox{$\pi^0$}\xspace}$ is $0.50 \pm 
0.01_{\rm stat} \pm 0.02_{\rm sys}$, constant, independent of collision centrality, and consistent with the previously measured values in hadron-hadron, hadron-nucleus, nucleus-nucleus as well as $e^{+}e^{-}$ collisions at $\sqrt{s_{_{NN}}}=$3–1800 GeV, suggesting that either the fragmentation of jets into and $\eta$ is unchanged irrespective of the absence or presence of the medium, or it changes the same way, despite the different flavor content. The values of $R_{AB}$ for and $\eta$ are consistent within uncertainties in all analyzed centrality intervals of ${\mbox{Cu$+$Au}\xspace}$ collisions. The suppression pattern of $\pi^0$ in ${\mbox{Cu$+$Au}\xspace}$ collisions is consistent with ${\mbox{Au$+$Au}\xspace}$ and ${\mbox{Cu$+$Cu}\xspace}$ collisions at the same interaction energy and similar values of $N_{\rm part}$.

We thank the staff of the Collider-Accelerator and Physics Departments at Brookhaven National Laboratory and the staff of the other PHENIX participating institutions for their vital contributions. We acknowledge support from the 