Testing the Universality of Fragmentation Functions
  Using fragmentation functions for charged pions, charged kaons, and (anti)protons recently extracted from experimental data of e^+e^- annihilation at the Z-boson resonance and at centre-of-mass energy root(s) = 29 GeV, we perform a global study of inclusive charged-hadron production in p anti-p, gamma p, and gamma gamma collisions at next-to-leading order in the parton model of quantum chromodynamics. Comparisons of our results with p anti-p data from CERN S p anti-p S and the Fermilab Tevatron, gamma p data from DESY HERA, and gamma gamma data from CERN LEP2 allow us to test the universality of the fragmentation functions predicted by the factorization theorem. Furthermore, we perform comparisons with (e^+e^-)-annihilation data from LEP2 so as to test the scaling violations predicted by the Altarelli-Parisi evolution equations. 
B.A. Kniehl, G. Kramer, B. Poetter