Pion Condensation and Alternating Layer Spin Model in Symmetric Nuclear Matter : Use of Extended Effective Nuclear Forces : Nuclear Physics

概要

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Pion condensation in the symmetric nuclear matter is investigated on the basis of the ALS (alternating-layer-spin) model which provides a good description for the π^0 condensation. We perform energy calculations in a realistic way where the isobar (Δ)-mixing, the short range effects and the exchange energy of the interaction are taken into account. The Δ-mixing effect is built in the model state as previously done in the neutron matter. We preferentially employ G-0 force of Sprung and Banerjee as an effective interaction in the nucleon sector and extend it to the sectors including Δ using the SU(4) quark model. We show that the exchange terms have an important difference between the neutron matter and the symmetric nuclear matter due to the fact that charged mesons come into play in the latter but not in the former. It is found that the critical density ρ_c is around 2.5 ρ_0 (ρ_0; the normal nuclear density) and the pressure of the condensed system remains positive. The mechanism of realization of the new phase is essentially the same as that shown in the neutron matter: The main energy gain comes from the direct tensor term enhanced by the Δ-mixing, which competes with and overwhelms the suppressive effects resulting mainly from the kinetic energy and the Δ-N mass difference. Aspects of this phase are discussed in connection with properties of the extended effective baryon-baryon potentials.
理論物理学刊行会の論文
1985-03-25