Proceedings of the fourth workshop on elementary-particle picture of the universe

The Fourth Workshop on Elementary-Particle Picture of the Universe was held at Tateyama National Rest House from November 22 to 25, 1989. The main purpose of this workshop focuses on most of current experimental and theoretical activities in non-accelerator particle physics and astrophysics. It is also aimed to promote effective collaborations between experimentalists and theorists in these fields. The solar neutrino problem and the dark matter problem are the most exciting subjects in the astroparticle physics. They threw some doubts on the standard theories of astrophysics and also particle physics. We picked up both problems in this workshop as main themes, and discussed what they are at present and how they can be solved. Cosmology gives stringent constraints on particle properties which are frequently plausible candidates to solve the astrophysical problems. However, it is scarce to argue about how to determine the cosmological parameters and their ambiguities. We had some talks for this subject given by astronomers. New experimental results and detector developments were also presented. The atmosphere of workshop was informal, and there were extensive discussions on the above subjects. We got the confirm response that experimental and theoretical research activities in astroparticle physics were increasing here in Japan. (J.P.N.)