Strangeness production in proton - proton and proton - nucleus collisions ∗

In these lectures we discuss the investigation of the strange meson production in protonproton (pp) and in proton-nucleus (pA) reactions within an effective Lagrangian model. The kaon production proceeds mainly via the excitations of N(1650), N(1710), and N(1720) resonant intermediate nucleonic states, in the collision of two initial state nucleons. Therefore, the strangeness production is expected to provide information about the resonances lying at higher excitation energies. For beam energies very close to the kaon production threshold the hyperon-proton final state interaction effects are quite important. Thus, these studies provide a check on the models of hyperon-nucleon interactions. The inmedium production of kaons show strong sensitivity to the self energies of the intermediate mesons.