论文标题
不可压缩的活性液的通用性：非本地剪应力的影响
Universality in Incompressible Active Fluid: Effect of Non-local Shear Stress
论文作者
论文摘要
在过去的几十年中，活性流体的相变引起了极大的关注。最近的结果表明[L. Chen等，New J. Phys。 17，042002（2015）]认为，不可压缩的活性流体中的订单disorder相变属于新的普遍性类别。在这项工作中，我们进一步研究了这种类型的相变，并专注于远程相互作用的影响。这是通过将非本地剪切应力引入流体动力描述来实现的，从而导致速度场的超延伸，并且可以通过执行征费步行的活动粒子而观察到。通过对一环近似中相应的响应功能进行扰动重新归一化组分析来得出临界区域中的通用性能。我们表明，非本地剪切应力的效果降低了模型的上限临界维度，并可能导致活性液自变义与属于属于不寻常的“远程模型A”普遍性类别的模型无关紧要。此外，当非本地性的程度足够高时，所有非线性都无关紧要，而平均场描述在任何空间维度上都是有效的。
Phase transitions in active fluids attracted significant attention within the last decades. Recent results show [L. Chen et al., New J. Phys. 17, 042002 (2015)] that an order-disorder phase transition in incompressible active fluids belongs to a new universality class. In this work, we further investigate this type of phase transition and focus on the effect of long-range interactions. This is achieved by introducing a non-local shear stress into the hydrodynamic description, which leads to superdiffusion of the velocity field, and can be viewed as a result of the active particles performing Levy walks. The universal properties in the critical region are derived by performing a perturbative renormalization group analysis of the corresponding response functional within the one-loop approximation. We show that the effect of non-local shear stress decreases the upper critical dimension of the model, and can lead to the irrelevance of the active fluid self-advection with the resulting model belonging to an unusual 'long-range Model A' universality class not reported before. Moreover, when the degree of non-locality is sufficiently high all non-linearities become irrelevant and the mean-field description is valid in any spatial dimension.
