| The many-body problem of strongly interacting particles in atomic nuclei and, more generally, in infinite nuclear matter will be investigated. The research will concentrate on unravelling and understanding the key ingredient to these studies, i.e. the nucleon-nucleon interaction and its modification in nuclear matter. This research is relevant for explaining the stability of neutron stars and the behaviour of matter in the early phase of the Universe. Background, relevance and implementation The free nucleon-nucleon interaction will be investigated in few-body systems. A number of issues are of high current interest: the role of virtual nucleon-resonance excitation at low energies the off-shell properties of the T-matrix the role of two-body effects such as meson-exchange currents the three-body force in simple systems the spin-dependent part of the nuclear force. These studies will be executed with experimental state-of-the-art equipment, primarily through measurements of the nucleon-nucleon bremsstrahlung. Alongside continuum states, we will study observables in bound states through the radiative capture process, with both real and virtual photons. In nuclear matter the free nucleon-nucleon interaction is modified by many-body correlations and the excitation of nucleon resonances. At high nuclear density partial chiral symmetry restoration may become significant. In collisions between atomic nuclei at low and high energy and in pion-nucleus reactions we will study: the energy dissipation by first-chance and multiple nucleon-nucleon collisions the temperature dependence on nuclear friction properties of nucleon resonances in cold nuclear matter the propagation of mesons and nucleon resonances in excited nuclear matter the in-medium modification of hadron masses and resonance widths. This research programme will be pursued with AGOR at KVI and at several European laboratories (GANIL, GSI, Jülich, TSL) with complementary (polarised) beam-target combinations. |
