摘要翻译：
我们研究了一个包括两自旋和四自旋平均场相互作用的广义各向同性XY模型。该模型可以在微正则系综中求解。结果表明，在一定的参数范围内，在固定能量下，模型的磁化强度会出现间隙，从而导致遍历性断裂。这种现象以前在各向异性和离散自旋模型中都有报道。计算了模型的熵，导出了微正则相图，显示了从铁磁性到顺磁无序相的一级相变的存在。发现在铁磁相和顺磁相中都发生了遍历性破缺。结果，系统在顺磁区表现出稳定的铁磁相，而在磁有序区表现出无序相。
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英文标题：
《Phase space gaps and ergodicity breaking in systems with long range
  interactions》
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作者：
Freddy Bouchet (INLN, Phys-ENS), Thierry Dauxois (Phys-ENS), David
  Mukamel (Weizmann Institute, Phys-ENS), Stefano Ruffo (Univ. Firenze,
  Phys-ENS)
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最新提交年份：
2007
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分类信息：

一级分类：Physics        物理学
二级分类：Statistical Mechanics        统计力学
分类描述：Phase transitions, thermodynamics, field theory, non-equilibrium phenomena, renormalization group and scaling, integrable models, turbulence
相变，热力学，场论，非平衡现象，重整化群和标度，可积模型，湍流
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英文摘要：
  We study a generalized isotropic XY-model which includes both two-spin and four-spin mean-field interactions. This model can be solved in the microcanonical ensemble. It is shown that in certain parameter regions the model exhibits gaps in the magnetization at fixed energy, resulting in ergodicity breaking. This phenomenon has previously been reported in anisotropic and discrete spin models. The entropy of the model is calculated and the microcanonical phase diagram is derived, showing the existence of first order phase transitions from the ferromagnetic to a paramagnetic disordered phase. It is found that ergodicity breaking takes place both in the ferromagnetic and the paramagnetic phases. As a consequence, the system can exhibit a stable ferromagnetic phase within the paramagnetic region, and conversely a disordered phase within the magnetically ordered region.
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PDF链接：
https://arxiv.org/pdf/711.0268