Universality class for a nonequilibrium state of matter: A d = 4 − epsilon expansion study of Malthusian flocks
Universality class for a nonequilibrium state of matter: A d = 4 − epsilon expansion study of Malthusian flocks
复制标题
非平衡物质状态的普遍性类别：A d = 4 – 马尔萨斯群的 epsilon 展开研究
作者：
Leiming Chen;Chiu Fan Lee;John Toner
我们表明，“马尔萨斯羊群”-即，在其运动期间“出生”和“死亡”的自推进实体（as.living生物）的连贯运动集合属于新的普遍class.in空间维度d > 2。我们计算了这个新的普适性的普适指数和标度律. class在d = 4 − \n展开中到O（\n），发现这些与之前的“规范”指数不同。没有出生和死亡的那些），并且显示出对于空间维度在2范围内的不可压缩群是成立的，具有相反的符号。我们的展开式在d = 3时应该是相当精确的，从而可以在我们的理论、模拟和实验之间进行精确的定量比较。
We show that “Malthusian flocks”—i.e., coherently moving collections of self-propelled entities (such as.living creatures) which are being “born” and “dying” during their motion—belong to a new universality class.in spatial dimensions d > 2. We calculate the universal exponents and scaling laws of this new universality.class to O(\epsilon) in a d = 4 − \epsilon expansion and find these are different from the “canonical” exponents previously.conjectured to hold for “immortal” flocks (i.e., those without birth and death) and shown to hold for.incompressible flocks with spatial dimensions in the range of 2 has opposite signs. Our expansion should be quite accurate in d = 3, allowing.precise quantitative comparisons between our theory, simulations, and experiments.