Strangeness production in hadron-nucleus reactions

Strange-particle production in hadron-nucleus reactions is discussed. Emphases are: (1) Although enhancements of strangeness production may be a good signature of exotic phenomena associated with highly-excited nuclear matter, one must carefully separate effects of secondary processes. An enhancement of Λ production in anti p-nucleus reactions observed in a KEK bubble-chamber experiment was explained by secondary processes. (2) Hyperon polarization provides a good tool to probe quark structures of hadrons and nuclei. A KEK experiment on hyperon-beam polarization indicated that the quark-diquark recombination model seemed to work not only at high energies but also at low energies. It is interesting to study possibilities and/or limitations of applying such parton-recombination pictures to low-energy phenomena in the target-rapidity region. (3) Hyperon polarization also provides a variety of applications to spin physics of hypernuclei. (orig.)