Figure data and code for "Universality of pseudo-Goldstone damping near critical points"

Real-time dynamics of strongly correlated systems, in particular its critical dynamics near phase transitions, have been always on the cutting edge of studies in diverse fields of physics, e.g., high energy physics, condensed matter, holography, etc. In this work, we investigate the critical damping of collective modes associated with spontaneous breaking of approximate symmetries, which are called pseudo-Goldstone modes, in strongly correlated systems. Using the Schwinger-Keldysh field theory, we find a universal pseudo-Goldstone damping via the critical O($N$) model that has never been found before by other approaches. Different from the conventional damping found in holography and hydrodynamics, the new one is controlled by critical fluctuations, hence is invisible in mean-field systems or strongly correlated systems with classical gravity duals. Since the critical damping depends solely on the universalities of the critical point, irrespective of the microscopic details, our conclusion should be applicable to a wide class of interacting systems.

强关联系统的实时动力学，尤其是其在相变附近的临界动力学，一直是高能物理、凝聚态、全息等多个物理领域研究的前沿课题。本研究中，我们探究了强关联系统中与近似对称性自发破缺相关的集体模式（即赝戈德斯通模式，pseudo-Goldstone modes）的临界阻尼现象。借助施温格-凯尔迪什场论，我们通过临界O(N)模型发现了一种普适的赝戈德斯通阻尼效应，这是其他方法此前从未发现的。与全息和流体力学中发现的传统阻尼不同，这种新型阻尼由临界涨落主导，因此在平均场系统或具有经典引力对偶的强关联系统中不可见。由于该临界阻尼仅依赖于临界点的普适性，与微观细节无关，我们的结论适用于广泛的相互作用系统。