Nuclear Enhancement ofπ0andηMesons Produced at Large Transverse Momenta

The authors have measured the large-$p_T$ inclusive cross sections for ${\pi }^0$ and $\eta$ production near 90° in the center-of-mass system in 200-GeV/c ${\pi }^{+}$ and proton collisions with beryllium, carbon, and aluminum targets. The cross section for both ${\pi }^0$ and $\eta$ mesons rises with increasing nucleon number ($A$) of the target nucleus as $A^{\alpha }$, with $\alpha >1\mathrm{}$. The ratio of the ${\pi }^0$ yield in $\mathrm{pA}$ collisions to that in ${\pi }^{+}A$ collisions decreases with increasing $p_T$.