background normalization, different fitting ranges, and different order polynomials for the residual background estimation. Some photons from $\pi^0$ and $\eta$ decays convert into $e^-e^+$ pairs when traversing through detector material. If this happens within the magnetic field, they are bent in opposite directions and can not be reconstructed as a single photon-like cluster in the EMCal. As a result, $\approx25\%$ of $\pi^0$ and $\eta$ mesons are lost. This effect is included in the efficiency calculation. The uncertainty on how accurately it is reproduced in the simulation is estimated to be $5.2\%$, and it is Type-C, because in the relevant energy range the conversion probability is almost constant.

Systematic uncertainties for $\eta/\pi^0$ ratios are included as a quadratic sum of the type-B uncertainties from $\pi^0$ and $\eta$ yields. Because type-C uncertainties of the $\pi^0$ and $\eta$ yields are 100% correlated between these particle measurements for all , this uncertainty cancels in the ratios. The $p_T$-correlated systematic uncertainties for $R_{AB}$ include both uncertainties from Cu$+$Au and $p$+$p$ measurements [@Adare:2007dg].

Invariant yields are obtained separately for PbSc and PbGl subsystems. The results are then averaged with weights defined by the quadratic sum of statistical and those systematic uncertainties that are uncorrelated between the 