论文标题
通用缩放现象中的稳定且不稳定的扰动远离平衡
Stable and unstable perturbations in universal scaling phenomena far from equilibrium
论文作者
论文摘要
我们研究了远离平衡的量子多体系统中与通用缩放现象相关的非热固定点周围扰动的动力学。对于3+1个时空维度中的N分量标量量子场理论，我们使用自洽的大N扩展到近代领导顺序确定稳定性缩放指数。我们的分析揭示了稳定和不稳定的扰动的存在，后者导致与红外固定点的准指数偏差。我们通过计算光谱函数来确定远程平衡的准粒子及其分散关系的塔。在线性响应理论的帮助下，我们证明了不稳定的动力学是由准粒子状态之间的弹性散射过程之间的竞争引起的。最终使固定点动态吸引人的是缩放不稳定性的现象，这是由于自相似的准粒子级联而导致的不稳定政权的普遍缩放。我们的结果从一开始就了解了自组织缩放现象中的新兴稳定性。
We study the dynamics of perturbations around nonthermal fixed points associated to universal scaling phenomena in quantum many-body systems far from equilibrium. For an N-component scalar quantum field theory in 3+1 space-time dimensions, we determine the stability scaling exponents using a self-consistent large-N expansion to next-to-leading order. Our analysis reveals the presence of both stable and unstable perturbations, the latter leading to quasi-exponential deviations from the fixed point in the infrared. We identify a tower of far-from-equilibrium quasi-particle states and their dispersion relations by computing the spectral function. With the help of linear response theory, we demonstrate that unstable dynamics arises from a competition between elastic scattering processes among the quasi-particle states. What ultimately renders the fixed point dynamically attractive is the phenomenon of a scaling instability, which is the universal scaling of the unstable regime towards the infrared due to a self-similar quasi-particle cascade. Our results provide ab initio understanding of emergent stability properties in self-organized scaling phenomena.
