Strange particles: A probe of new physics in particles and nuclei

Abstract

Nuclear and also partially particle physics with strangeness is surveyed with emphasis on the following points: In Λ and Σ hypernuclei one can determine the hyperon-nucleus interaction and learn something on the spin-orbit strength of the hyperon-nucleus potential. This yields information on the hyperon-nucleon interaction. Not understood is the small width of the Σ-hypernuclei. From doubly strange nuclei one could learn something about the hyperon-hyperon interaction and get information about the reaction dynamics of double strangeness exchange reactions. An especially interesting double strange system is the H-Dibaryon which has the quark content of two Λ's. Is this system bound below the ΛΛ threshold? The proton-antiproton reaction going to lambda-antilambda which is studied at LEAR gives information about the proton-antiproton annihilation mechanism and the creation of a strange-antistrange quark pair. On the long run, one should also think of looking for charmed hypernuclei. The K + meson is the weak interacting particle of the strong interaction. Thus, one can probe matter distribution of a nucleus even deep inside, similar to the electron-nucleus scattering which maps the charge distributions of the nuclei. As a last: point, quark-gluon spectroscopy is discussed at the example of the Λ ∗( 3 2 −; 1520 MeV) . Reactions with strange projectiles can probe the nature of the wave functions of different baryonic and hadronic excited states. In the same way one was probing in nuclear physics the nature of different states by exciting them in projectile nucleus scattering and measuring the di-excitation gamma rays.