Measurement of ${\pi }^0$ production at large transverse momentum in ${\pi }^{\mathrm{-}}$p, ${\pi }^{+}$p, and pp collisions at 300 GeV/c

Cross sections for inclusive ${\pi }^0$ production at large transverse momentum $p_T$ were measured in ${\pi }^{\mathrm{-}}$p, ${\pi }^{+}$p, and pp collisions at 300 GeV/c. The cross-section ratio σ(${\pi }^{-}$p→${\pi }^0$X)/σ(${\pi }^{+}$p→${\pi }^0$X) was found to be consistent with unity in the $p_T$ region of 1 to 5 GeV/c. The cross-section ratio σ(${\pi }^{+}$p→${\pi }^0$X)/σ(pp→${\pi }^0$X) however is growing with increasing $p_T$ and increasing ${\pi }^0$ c.m.-system rapidity in agreement with parton-model expectations, where the partons in the pions have on average higher momenta than in the proton.