论文标题
水浪波中的现场理论旋转和动量
Field-theory spin and momentum in water waves
论文作者
论文摘要
自旋是量子粒子或磁场的基本但非平凡的内在角度特性，它出现在相对论场理论中。波场中的自旋密度是根据规范和动力动量密度之间的差异来描述的。这些数量通常被认为是抽象和不可观察的本身。在这里，我们在理论上和实验上都证明了Belinfante-Rosenfeld的结构自然出现在重力（水面）波中。在那里，规范动量与广义的stokes-Drift现象有关，而自旋是由水颗粒的亚波长圆运动产生的。因此，我们直接将这些基本的现场理论特性视为经典波系统的微观机械性能。我们的发现阐明了波浪场中的自旋和动量的性质，展示了相对论现场理论概念的普遍性，并为他们的研究提供了一个新的平台。
Spin is a fundamental yet nontrivial intrinsic angular-momentum property of quantum particles or fields, which appears within relativistic field theory. The spin density in wave fields is described by the theoretical Belinfante-Rosenfeld construction based on the difference between the canonical and kinetic momentum densities. These quantities are usually considered as abstract and non-observable per se. Here, we demonstrate, both theoretically and experimentally, that the Belinfante-Rosenfeld construction naturally arises in gravity (water surface) waves. There, the canonical momentum is associated with the generalized Stokes-drift phenomenon, while the spin is generated by subwavelength circular motion of water particles. Thus, we directly observe these fundamental field-theory properties as microscopic mechanical properties of a classical wave system. Our findings shed light onto the nature of spin and momentum in wave fields, demonstrate the universality of relativistic field-theory concepts, and offer a new platform for their studies.
