Parameterizations of Invariant Meson Production Cross Section
  The Lund string fragmentation model is applied in a non-perturbative calculation of the invariant production cross section of pions from proton-proton collisions in the soft pT region. Invariant production cross sections of pions and kaons from proton-proton collisions in the hard pT region are calculated from the Feynman-Field perturbative QCD parton model. Parameterizations of these production invariant cross sections are described. 
Alfred Tang and John W. Norbury