Production of ${\pi }^0$ and $\eta$ mesons in Cu$+$Au collisions at $\sqrt{s_{{}_{NN}}}$=200 GeV

Production of ${\pi }^0$ and $\eta$ mesons has been measured at midrapidity in Cu$+$Au collisions at $\sqrt{s_{{}_{NN}}}$=200 GeV. Measurements were performed in ${\pi }^0(\eta )\to \gamma \gamma$ decay channel in the 1(2)-20 GeV/$c$ transverse momentum range. A strong suppression is observed for ${\pi }^0$ and $\eta$ meson production at high transverse momentum in central Cu$+$Au collisions relative to the $p$$+$$p$ results scaled by the number of nucleon-nucleon collisions. In central collisions the suppression is similar to Au$+$Au with comparable nuclear overlap. The $\eta \mathrm{/}{\pi }^0$ ratio measured as a function of transverse momentum is consistent with $m_T$-scaling parameterization down to $p_T=$2 GeV/$c$, its asymptotic value is constant and consistent with Au$+$Au and $p$$+$$p$ and does not show any significant dependence on collision centrality. Similar results were obtained in hadron-hadron, hadron-nucleus, and nucleus-nucleus collisions as well as in $e^{+}{e}^{-}$ collisions in a range of collision energies $\sqrt{s_{{}_{NN}}}=$3–1800 GeV. This suggests that the quark-gluon-plasma medium produced in Cu$+$Cu collisions either does not affect the jet fragmentation into light mesons or it affects the ${\pi }^0$ and $\eta$ the same way.