Strangeness Production and Flow in Heavy-Ion Collisions
With the development of various heavy-ion facilities, nuclear physics is expanding into many new directions. One of these is the study of the properties of strange particles, namely hyperons and kaons, in dense matter. Strangeness plays a special role in the development of hadronic and nuclear models. The mass of strange quark is about 150 MeV, which is, on the one hand, considerably larger than the mass of light (up and down) quarks (∼ 5 MeV), but on the other hand, much smaller than that of charm quark (∼ 1.5 GeV). In the limit of vanishing quark mass the chiral symmetry is good, and systematic studies can be carried out using chiral perturbation theory for hadrons made of light quarks. On the other hand, if the quark mass is large, one can use the non-relativistic quark model to study the properties of charmed and heavier hadrons. The hadrons with strangeness lie in between these two limits and therefore present a challenge to the theorists.