This Letter reports measurements of the ratios of $\pi$, $K$, and $p$ production at large values of transverse momentum in ${\pi }^{-}-p$ collisions. The charge ratios, such as $\frac{{\pi }^{-}}{{\pi }^{+}}$, $\frac{K^{-}}{K^{+}}$, and $\frac{\overline{p}}{p}$ are seen to be quite different from those measured in $p-p$ collisions. These ratios are sensitive tests of hard-scattering models, and are compared with the-oretical predictions. The particle ratios have also been studied as a function of center-of-mass angle (${\theta }^{*}$) at ${\theta }^{*}=90\mathrm{}°, 77°, \mathrm{and} 60°$.

• Received 4 December 1979

DOI:https://doi.org/10.1103/PhysRevLett.44.511