Theoretical Aspects of Inclusive Light-Hadron Production

Abstract

We summarize the key results of a recent global analysis of inclusive single-charged-hadron production in high-energy colliding-beam experiments. In the framework of the parton model of quantum chromodynamics at next-to-leading order (NLO), fragmentation functions (FFs) for charged pions, charged kaons, and (anti) protons are extracted from experimental data of e^+e^- annihilation at the Z-boson resonance and at centre-of-mass energy root(s) = 29 GeV. This fit also yields a new NLO value for the strong-coupling constant, namely alpha_s^(5)(M_Z) = 0.1170 +- 0.0073. The scaling violations encoded in the FFs through the Altarelli-Parisi evolution equations are tested by confronting (e^+e^-)-annihilation data from DESY DORIS, DESY PETRA, and CERN LEP2 with NLO predictions based on these FFs. Comparisons of p p-bar data from CERN S p p-bar S and the Fermilab Tevatron, gamma p data from DESY HERA, and gamma gamma data from LEP2 with the corresponding NLO predictions allow us to test the universality of the FFs predicted by the factorization theorem.