论文标题
太近的集成：从正常到异常的热量扩散
Too Close to Integrable: Crossover from Normal to Anomalous Heat Diffusion
论文作者
论文摘要
具有三种保护定律的颗粒的一维链中的能量传输通常是异常的，并且属于Kardar-Parisi-Zhang动力学类别。令人惊讶的是，在大量长度尺度上发现了一些明显的正常热扩散的例子。我们提出了对这些有趣的观察的新颖物理解释。我们开发了一个扩展分析，该分析解释了在可集成极限的附近发生的情况，例如，不仅是著名的Toda模型。在此限制下，热传输主要是由准粒子提供的，其平均自由路径$ \ ell $非常大。在增加系统尺寸$ l $后，可以观察到三种不同的策略：弹道式扩散范围，最终是异常（流体动力学）制度的交叉。我们的理论考虑得到了对几乎相等质量和弱扰动TODA链的双原子硬点颗粒气体的数值模拟的支持。最后，我们讨论了扰动的谐波链的情况，该链链表现出不同的情况。
Energy transport in one-dimensional chains of particles with three conservation laws is generically anomalous and belongs to the Kardar-Parisi-Zhang dynamical universality class. Surprisingly, some examples where an apparent normal heat diffusion is found over a large range of length scales were reported. We propose a novel physical explanation of these intriguing observations. We develop a scaling analysis which explains how this may happen in the vicinity of an integrable limit, such as, but not only, the famous Toda model. In this limit, heat transport is mostly supplied by quasi-particles with a very large mean free path $\ell$. Upon increasing the system size $L$, three different regimes can be observed: a ballistic one, an intermediate diffusive range, and, eventually, the crossover to the anomalous (hydrodynamic) regime. Our theoretical considerations are supported by numerical simulations of a gas of diatomic hard-point particles for almost equal masses and of a weakly perturbed Toda chain. Finally, we discuss the case of the perturbed harmonic chain, which exhibits a yet different scenario.
