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, we 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 us 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+ecollisions, one can deduce the shape of fragmentation spectra in soft hadronic collisions. However, hadronic collisions 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 Plab > 200 GeV/c in particular from strange beams.
To explain the occurrence of the sharp cusp of the low-field susceptibility of spin glasses, some theories have been put forward which lead to a special type of phase transition at a critical temperature 7,. We show that the straightforward application of such theories to deduce the magnetic part c, of the specific heat leads to some anomaly of this quantity at 7,. More accurate measurements of c, and x near 7, are necessary. At the moment it looks like a contradiction between theory and experiment.
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