![image](FIG4_CuAu_pi0_eta_RAB_rev3_1cp.pdf){width="0.99\linewidth"}

![image](FIG5_CuAu_AuAu_CuCu_pi0_RAB_rev3_1cp.pdf){width="0.99\linewidth"}

![image](fig7.pdf){width="0.99\linewidth"}

Results and discussion
======================

Invariant yields in the range 1(2)-20for $\pi^0$ ($\eta$) mesons measured in different centrality intervals and MB collisions are shown in panels (a) and (e) of Fig. \[fig:FIG1\_CuAu\_CY\], respectively. At low the measurement is limited by the rapidly decreasing $S/B$ ratio, and at high by the available statistics.

Spectra of $\pi^0$ and $\eta$ mesons can be fitted with a sum of Hagedorn and power-law functions: $$f(p_T)=T(p_T)\frac{A}{(1+p_T/p_0)^m}+(1-T(p_T))\frac{B}{p^n_T},$$

where $T(p_T)=1/(1+\exp((p_T-t)/w))$, $A$, $p_0$, $m$, $B$, $n$, $t$ and $w$ are free parameters. The parameter $t$ governs at what the second, pure power-law term becomes dominant; $t$ varies between 4–6, depending on centrality. The parameter $w$ varies between 0.05–0.15 and governs the width of transition interval, where the first term loses its dominance and the second term becomes dominant. At high transverse momenta $f(p_T) \propto {\mbox{$p_T$}\xspace}^{-n}$. For in MB collisions $n=8.06 \pm 0.01_{\rm stat} \pm 0.06_{\rm sys}$, for the most central 0%–10% collisions $n=8.02 \pm 0.02_{\rm stat} \pm 0.07_{\rm sys}$, and increases slowly to $n=8.07 \pm 0.02_{\rm stat} \pm 0.06_{\rm sys}$ up to 40% centrality. These numbers are consistent within uncertainties to the values obtained in pure power-law fits at high ($>$8) in 200GeV collisions with similar  [@Adare:2008qa; 