摘要翻译：
我们引入了一个新的铁磁模型，它能够再现椋鸟群体集体行为的一个最有趣的性质，即系统的强集体有序性与微观自由度模量的无标度关联共存，即鸟的速度。新理论的核心思想是将微观自由度的模量限定在有限值附近所需的单粒子势是边际的，即曲率为零。我们利用三维平均场近似和蒙特卡罗模拟，并辅以有限尺度分析来研究该模型。当在标准临界温度$T_c$时，边缘模型的性质与正常铁磁体的连续对称破缺完全相同，结果表明，在深有序相中，边缘模型出现了一个新的零温临界点，从而使其微观自由度模量的发散磁化率和相关长度与椋鸟自然种群的实验数据完全相似。
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英文标题：
《Low-temperature marginal ferromagnetism explains anomalous scale-free
  correlations in natural flocks》
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作者：
Andrea Cavagna and Antonio Culla and Luca Di Carlo and Irene Giardina
  and Tomas S. Grigera
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最新提交年份：
2019
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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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一级分类：Physics        物理学
二级分类：Biological Physics        生物物理学
分类描述：Molecular biophysics, cellular biophysics, neurological biophysics, membrane biophysics, single-molecule biophysics, ecological biophysics, quantum phenomena in biological systems (quantum biophysics), theoretical biophysics, molecular dynamics/modeling and simulation, game theory, biomechanics, bioinformatics, microorganisms, virology, evolution, biophysical methods.
分子生物物理、细胞生物物理、神经生物物理、膜生物物理、单分子生物物理、生态生物物理、生物系统中的量子现象（量子生物物理）、理论生物物理、分子动力学/建模与模拟、博弈论、生物力学、生物信息学、微生物、病毒学、进化论、生物物理方法。
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一级分类：Quantitative Biology        数量生物学
二级分类：Other Quantitative Biology        其他定量生物学
分类描述：Work in quantitative biology that does not fit into the other q-bio classifications
不适合其他q-bio分类的定量生物学工作
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英文摘要：
  We introduce a new ferromagnetic model capable of reproducing one of the most intriguing properties of collective behaviour in starling flocks, namely the fact that strong collective order of the system coexists with scale-free correlations of the modulus of the microscopic degrees of freedom, that is the birds' speeds. The key idea of the new theory is that the single-particle potential needed to bound the modulus of the microscopic degrees of freedom around a finite value, is marginal, that is has zero curvature. We study the model by using mean-field approximation and Monte Carlo simulations in three dimensions, complemented by finite-size scaling analysis. While at the standard critical temperature, $T_c$, the properties of the marginal model are exactly the same as a normal ferromagnet with continuous symmetry-breaking, our results show that a novel zero-temperature critical point emerges, so that in its deeply ordered phase the marginal model develops divergent susceptibility and correlation length of the modulus of the microscopic degrees of freedom, in complete analogy with experimental data on natural flocks of starlings.
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PDF链接：
https://arxiv.org/pdf/1812.07522