Single-Pion Production at 100 GeV/c: A Detailed Test of Factorization

A relatively bias-free comparison is made of inclusive and semi-inclusive charged-pion single-particle spectra in ${\pi }^{+}p$ and $\mathrm{pp}$ interactions. Inclusive Mueller factorization is satisfied by ${\pi }^{-}$ but not ${\pi }^{+}$ production. Factorization holds for proton-target fragmentation into ${\pi }^{-}$ for a fixed number of ${\pi }^{-}$ backward in the c.m. system, but not for fixed total multiplicity. In the central region, ${\pi }^{+}p\to {\pi }^{\pm }$ shows an $s^{-\frac{1}{4}}$ approach to the same value, ∼ 0.78, seen in other reactions.