Phase Transition of High Density Matter in the Universe

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Results of the present research are summarized in the following three group. 1) Early Universe: A new method for quantum cosmology, in which the time is explicitly appeared and the probability is always positive definite, was formulated (Hosoya). Baryogenesis in the inflationary universe was investigated systematically. It was found that i) non thermal effects in the reheating stage play an important role, ii) in the chaotic inflationary scenario, baryon number domain structure might be formed (Sato). Evolution of density fluctuations which are formed by the phase transition in the early universe was investigated and the constraints on the model imposed from the homogeneity of 3k background radiation was made clear (Sasaki). Nucleosynthesis in the lepton-number asymmetric universe was investigated and it was found that more stringent constraints on the asymmetry is obtained.2) Supernova and Neutron Star: Theoretical analysis of neutrino burst from the Supernova 1987A was made and it was found that i) the burst is surprisingly consistent with theoretical prediction, ii) The mass of neutron star just born might be 1.2-1.6M, iii) The mass of electron type neutrinos mast be smaller than 26 eV (Sato). Monte Calro simulation of finite temperature quark gluon plasma was made and it was found that the transition is of first order (UKawa).3) High density plasma: Two phase separation (hydrogen and iron ions) in the center of the sun was investigated and it was found this separation does not occur (Ichimaru). Neutrino loss rate was calculated in detail on the basis of Weinberg-Salam theory (Itoh).