Chapter VII Neutral Pion Condensation in Hot and Dense Nuclear Matter

概要

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From a viewpoint of the effective interaction and the equivalence between the potential and the field descriptions, a framework to treat the π^0 condensation at finite temperature is presented. This framework is based on the finite-temperature Hartree-Fock method with use of effective two-nucleon potentials. It is successfully applied to the ALS model of π^0 condensate and can be extended to the case including explicitly the isobar Δ(1232) degrees of freedom. In the studies on neutron matter, symmetric nuclear matter and supernova matter, the following points are found; (i) the transition density of π^0 condensation increases remarkably with the temperature, (ii) the cause is a reduction of entropy in the ordered π^0-condensed phase, (iii) the transition is of first-order and the phase diagram contains a wide mixed phase region, (iv) the equation of state is significantly softened even at finite temperature by the phase transition. A comment is given on the stability of the π^0-condensed phase in macroscopic scale relevant to supernova cores or very hot neutron stars. Also a possibility to realize the π^-0 condensate in laboratories by energetic nucleus-nucleus collisions is briefly discussed.
理論物理学刊行会の論文
1993-06-20