In the last five years ample evidence has been found supporting the idea that the quark-parton structure of hadrons is relevant for multiple production in soft hadronic collisions. Starting from the experimental foundations, the authors compare the most successful models applying this idea. Implications are discussed on special type reactions like diffraction dissociation and collisions on nuclei, and the models are confronted with recent data leading to new insight and modifications. Relative yields of particles in the central region may be understood as reflecting their valence quark structure in the framework of quark combinatorics, and the comparison of the valence structure of initial and final hadrons allows one to understand yields in the fragmentation regions. From the structure functions of initial hadrons and/or the fragmentation functions of (di)quarks into final hadrons as seen in deep inelastic lepton-hadron or e+e- collisions, one can deduce the shape of fragmentation spectra in soft hadronic collisions. However, hadronic oscillations also prove a very rich independent source of information on parton structure. Work to be done on the theoretical side is on a solid foundation of the two successful pictures of quark fragmentation and quark recombination as well as on an explanation of their apparent complementarity. On the experimental side, apart from further results from the pp collider, high statistics is needed on hydrogen and on heavier nuclei at rho lab>200 GeV/c in particular from strange beams.

https://iopscience.iop.org/article/10.1088/0034-4885/46/11/001/pdf

Parton models of low momentum transfer processes

Evidence for dominant vector-meson production in inelastic proton-proton collisions at 53 GeV c.m. energy

Inclusive production of non-strange mesons in pp annihilations

A study of direct and indirect pion production in π+p interactions at 16 GeV/c

We report on a study of ρ0, ρ+, ω,\(\bar K^{*0} (892)\) andK*0 (892) inclusive production in π+p interactions at 250 GeV/c, for ρ+,\(\bar K^{*0} (892)\) for the first time in a π+p experiment. The data are compared withK+p data in the same experiment, with results of other experiments and with quark-parton models. Interesting differences are found between ρ+,0 and ω production.

Inclusive production of vector mesons in π + p interactions at 250 GeV/c

https://cds.cern.ch/record/693645/files/197605156.pdf

E. Leitner

Papers

Production of ρ0 and f in π−p interactions at 16 GeV/c and separation into fragmentation and central components