Tests of the quark-parton model in soft hadronic processes

A simple quark-antiquark recombination model is used to predict some features of two-particle inclusive cross sections in the fragmentation region in soft hadronic processes. We compare ${\pi }^{+}$ cross sections observed at Feynman $x_b$ in association with various "trigger" particles (at $x_a$) and discuss the dependence of the cross sections on an approximate scaling variable ${\tilde{x}}_b=\frac{x_b}{(1-x_a)}$. Data from 360-GeV/c ${\pi }^{-}p$ interactions are consistent with our predictions.