标题： 涡旋粒子在加速器中的角动量动力学 显示英文标题

标题： Angular momentum dynamics of vortex particles in accelerators

摘要： 带有自旋极化的轻子和强子束的实验通常使用具有确定动量和能量的平面波态。 相反，涡旋态代表携带沿传播方向具有明确轨道角动量投影的圆柱波。 这种投影可以非常大，使这些粒子具有比平面波态大几个数量级的磁矩。 因此，涡旋粒子可能在高能碰撞中补充——甚至取代——自旋极化束，从而获得传统态无法达到的可观测量。 尽管相对论涡旋束尚未实现，我们研究了加速器中涡旋粒子的辐射和非辐射角动量动力学。 我们计算了通过光子发射导致角动量损失的时间尺度，发现它显著长于典型的加速时间。 非辐射动力学由进动主导，轨道角动量的进动频率与自旋的进动频率明显不同。 类似于环形加速器中的自旋调谐，这可能会引起共振，破坏束流的轨道动量——对于涡旋束来说，这种情况比自旋极化束出现得更加频繁。 因此，涡旋粒子在直线加速器中加速可能更为可行，而西伯利亚蛇可作为角动量操控的工具。 显示英文摘要

摘要： Experiments with spin-polarized beams of leptons and hadrons typically employ plane-wave states with definite momenta and energies. In contrast, vortex states represent cylindrical waves carrying a well-defined orbital angular momentum projection along the propagation direction. This projection can be arbitrarily large, endowing such particles with magnetic moments orders of magnitude greater than those of plane-wave states. Consequently, vortex particles could complement - or even replace - spin-polarized beams in high-energy collisions, enabling access to observables beyond the reach of the conventional states. Although relativistic vortex beams have yet to be realized, we investigate the radiative and non-radiative dynamics of angular momentum for vortex particles in accelerators. We compute the timescale for angular momentum loss via photon emission, finding it significantly longer than typical acceleration times. The non-radiative dynamics is governed by precession, with the orbital angular momentum precessing at a frequency markedly different from that of spin. Similar to spin tunes in circular accelerators, this can induce resonances that disrupt the beam's orbital momentum - occurring far more frequently for vortex beams than for spin-polarized ones. Thus, vortex particle acceleration can be more feasible in linacs, while Siberian snakes could serve as a tool for angular momentum manipulations.