论文标题
极性羊群对空间各向异性的敏感性
Susceptibility of Polar Flocks to Spatial Anisotropy
论文作者
论文摘要
我们通过研究有两个维度的活动$ Q $状态型号来考虑空间各向异性对极性羊群的影响。与平衡中发生的情况相反，我们发现，在大尺寸的限制中，任何数量的各向异性都大大变化了旋转不变的情况的现象学，破坏了远距离相关性，钉住了全球秩序的方向，并将共存阶段的行进带转换为单个移动域。所有这些都发生在$ q \至\ infty $限制中的长度范围之外。因此，可以在有限的系统中观察到类似于Vicsek模型的现象学，以足够大的$ Q $。我们提供了一个缩放论点，该论点合理化了为什么各向异性在被动和主动案例中具有如此不同的影响。
We consider the effect of spatial anisotropy on polar flocks by investigating active $q$-state clock models in two dimensions. In contrast to what happens in equilibrium, we find that, in the large-size limit, any amount of anisotropy changes drastically the phenomenology of the rotationally-invariant case, destroying long-range correlations, pinning the direction of global order, and transforming the traveling bands of the coexistence phase into a single moving domain. All this happens beyond a lengthscale that diverges in the $q\to\infty$ limit. A phenomenology akin to that of the Vicsek model can thus be observed in a finite system for large enough values of $q$. We provide a scaling argument which rationalizes why anisotropy has so different effects in the passive and active cases.
