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A hierarchical mean field model of interacting spins
Stochastic Processes and their Applications ( IF 1.1 ) Pub Date : 2021-07-03 , DOI: 10.1016/j.spa.2021.06.011
Paolo Dai Pra 1 , Marco Formentin 1, 2 , Guglielmo Pelino 1, 3
Affiliation  

We consider a system of hierarchical interacting spins under dynamics of spin-flip type with a ferromagnetic mean field interaction, scaling with the hierarchical distance, coupled with a system of linearly interacting hierarchical diffusions of Ornstein–Uhlenbeck type. In particular, the diffusive variables enter in the spin-flip rates, effectively acting as dynamical magnetic fields. In absence of the diffusions, the spin-flip dynamics can be thought of as a modification of the Curie–Weiss model. We study the mean field and the two-level hierarchical model, in the latter case restricting to a subcritical regime, corresponding to high temperatures, obtaining macroscopic limits at different spatio-temporal scales and studying the phase transitions in the system. We also formulate a generalization of our results to the kth level hierarchical case, for any k finite, in the subcritical regime. We finally address the supercritical regime, in the zero-temperature limit, for the two-level hierarchical case, proceeding heuristically with the support of numerics.



中文翻译:

相互作用自旋的分层平均场模型

我们考虑在自旋翻转型动力学下的分级相互作用自旋系统,具有铁磁平均场相互作用,随分级距离缩放,再加上 Ornstein-Uhlenbeck 型线性相互作用分级扩散系统。特别是,扩散变量进入自旋翻转率,有效地充当动态磁场。在没有扩散的情况下,自旋翻转动力学可以被认为是居里-魏斯模型的修改。我们研究平均场和两级层次模型,在后一种情况下,限于亚临界状态,对应于高温,获得不同时空尺度的宏观极限并研究系统中的相变。我们还将我们的结果概括为第 层 层级情况,对于任何 有限,在亚临界状态。我们最终在零温度极限下解决了两级分层情况下的超临界状态,在数值的支持下启发式地进行。

更新日期:2021-07-12
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