Example $M(\gamma\gamma)$ distribution in forward $p$-Pb collisions at $\sqrt{s_{\rm NN}}=8.16 \text{ Te V} $ for $2.5<\eta_{\rm c.m.}<3.5$ and $2.0< p_{\mathrm{T}} (\pi ^0 )<2.2 \text{ Ge V} $. Fit results are overlaid with the total fit shown as a solid line. The combinatorial (Comb.) and bremsstrahlung (Brem.) backgrounds are shown as light and dark shaded regions, respectively.

Measured $\pi ^0 $ differential cross sections versus $ p_{\mathrm{T}} $ in the (top) backward and (bottom) forward $\eta_{\rm c.m.}$ regions. Statistical uncertainties are shown by error bars, while systematic uncertainties are shown by boxes. The $pp$ cross sections are scaled by the atomic mass of the lead ion, $A=208$.

Measured $\pi ^0 $ nuclear modification factor in the (left) backward and (right) forward $\eta_{\rm c.m.}$ regions. Error bars show the statistical uncertainty, while the open boxes show the $ p_{\mathrm{T}}$ -dependent systematic uncertainties. The solid gray boxes show the overall normalization uncertainties from the luminosity estimate and efficiency correction factors. The results are compared to (top) theoretical predictions [47,49,52] and (bottom) to charged-particle data from Ref. [15]. The hatched regions show the NPDF uncertainties of the PQCD calculations. The vertical error bars on the charged-particle results show the combined systematic and statistical uncertainties.

Measured $\pi^0$ nuclear modification factor in the (left) backward and (right) forward $\eta_{\rm CM}$ regions. The error bars show the statistical uncertainties, while the open boxes show the $ p_{\mathrm{T}}$ -dependent systematic uncertainties. The solid black boxes show the overall normalization uncertainties from the luminosity estimate and efficiency correction factors. The measurements are compared to NLO PQCD predictions [47] calculated using the EPPS16 [2] and nCTEQ15 [3] NPDF sets.

Animated gif made out of all figures.

Relative systematic and statistical uncertainties in $d\sigma/d p_{\mathrm{T}} $ and $R_{p -{\rm Pb}}$ in percent. The ranges correspond to the minimum and maximum values of the associated uncertainties across all $ p_{\mathrm{T}} $ intervals and both $\eta_{\rm c.m.}$ regions. The $d\sigma/d p_{\mathrm{T}} $ ranges cover the uncertainties for each of the $p$-Pb and $pp$ samples. All sources of systematic uncertainty are fully correlated across $ p_{\mathrm{T}} $ intervals.

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