Density-induced suppression of the α-particle condensate in nuclear matter and the structure of α-cluster states in nuclei
Density-induced suppression of the α-particle condensate in nuclear matter and the structure of α-cluster states in nuclei
复制标题
核物质中α粒子凝聚体的密度诱导抑制和原子核中α簇态的结构
DOI：
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
T. Yamada
中科院分区：
文献类型：
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作者：
Y. Funaki;Hisashi Horiuchi;Hisashi Horiuchi;G. Röpke;Peter Schuck;A. Tohsaki;T. Yamada
At low densities, with decreasing temperatures, in symmetric nuclear matter \ensuremath{\alpha} particles are formed, which eventually give raise to a quantum condensate with four-nucleon \ensuremath{\alpha}-like correlations (quartetting). Starting with a model of \ensuremath{\alpha} matter, where undistorted \ensuremath{\alpha} particles interact via an effective interaction such as the Ali-Bodmer potential, the suppression of the condensate fraction at zero temperature with increasing density is considered. Using a Jastrow-Feenberg approach, it is found that the condensate fraction vanishes near saturation density. Additionally, the modification of the internal state of the \ensuremath{\alpha} particle due to medium effects will further reduce the condensate. In finite systems, an enhancement of the $S$-state wave function of the center-of-mass orbital of \ensuremath{\alpha}-particle motion is considered as the correspondence to the condensate. Wave functions have been constructed for self-conjugate $4n$ nuclei that describe the condensate state but are fully antisymmetrized on the nucleonic level. These condensate-like cluster wave functions have been successfully applied to describe properties of low-density states near the $n\ensuremath{\alpha}$ threshold. Comparison with orthogonality condition model calculations in $^{12}\mathrm{C}$ and $^{16}\mathrm{O}$ shows strong enhancement of the occupation of the $S$-state center-of-mass orbital of the \ensuremath{\alpha} particles. This enhancement is decreasing if the baryon density increases, similar to the density-induced suppression of the condensate fraction in \ensuremath{\alpha} matter. The ground states of $^{12}\mathrm{C}$ and $^{16}\mathrm{O}$ show no enhancement at all, thus a quartetting condensate cannot be formed at saturation densities.
At low densities, with decreasing temperatures, in symmetric nuclear matter \ensuremath{\alpha} particles are formed, which eventually give raise to a quantum condensate with four-nucleon \ensuremath{\alpha}-like correlations (quartetting). Starting with a model of \ensuremath{\alpha} matter, where undistorted \ensuremath{\alpha} particles interact via an effective interaction such as the Ali-Bodmer potential, the suppression of the condensate fraction at zero temperature with increasing density is considered. Using a Jastrow-Feenberg approach, it is found that the condensate fraction vanishes near saturation density. Additionally, the modification of the internal state of the \ensuremath{\alpha} particle due to medium effects will further reduce the condensate. In finite systems, an enhancement of the $S$-state wave function of the center-of-mass orbital of \ensuremath{\alpha}-particle motion is considered as the correspondence to the condensate. Wave functions have been constructed for self-conjugate $4n$ nuclei that describe the condensate state but are fully antisymmetrized on the nucleonic level. These condensate-like cluster wave functions have been successfully applied to describe properties of low-density states near the $n\ensuremath{\alpha}$ threshold. Comparison with orthogonality condition model calculations in $^{12}\mathrm{C}$ and $^{16}\mathrm{O}$ shows strong enhancement of the occupation of the $S$-state center-of-mass orbital of the \ensuremath{\alpha} particles. This enhancement is decreasing if the baryon density increases, similar to the density-induced suppression of the condensate fraction in \ensuremath{\alpha} matter. The ground states of $^{12}\mathrm{C}$ and $^{16}\mathrm{O}$ show no enhancement at all, thus a quartetting condensate cannot be formed at saturation densities.