Inclusive pion production in relativistic proton collisions with nuclei, a reexamination

Various data for the $\mathrm{pA}\to {\pi }^{\pm }X$ reaction are examined with emphasis on viewing these data in a light most useful for understanding $\pi$ production in heavy ion collisions. The 730 MeV (proton energy) results of Cochrane et al. are found to display a large amount of scaling—if plotted as a function of the Feynman variable $x_R$ and if the $k_{\perp }$ behavior is removed. Viewed in this matter, the larger $x_R$ behavior of the 730 MeV data agree well with the 1-5 GeV data of Papp et al. In the forward hemisphere $\pi$ production from nuclei appears simply related to nucleon-nucleon $\pi$ production and is consistent with the limiting behavior of hard collision models. In the backward hemisphere, there is evidence for nuclear structure effects and clustering phenomena not included in hard collision models.