论文标题
电磁场中相对论电子自旋的动力学
Dynamics of the relativistic electron spin in an electromagnetic field
论文作者
论文摘要
相对论旋转操作员不能在相对论量子力学中唯一定义。以前，已经提出了不同适当的相对论自旋算子，例如折叠式 - 杜斯林的自旋算子和Pryce型，它们都用自由粒子的Dirac Hamiltonian上下班，并且代表了运动的常数。在这里，我们考虑了外部电磁场中相对论电子自旋的动力学。我们使用两种不同的汉密尔顿人来得出相应的自旋动力学。这两个是：（a）在存在外场的情况下，狄拉克汉密尔顿人，（b）同一的半循环膨胀。考虑到褶皱的旋转和pryce旋转算子，我们表明，这些导致外部电磁场中不同的旋转动力学，这提供了区分其作用的可能性。我们发现，旋转算子的动力学涉及自旋依赖性和独立于自旋的术语，但是，折叠式旋转动力学还解释了相对论的粒子 - 安属粒子耦合。我们得出的结论是，Pryce旋转操作员在弱到中等外部场中提供了相对论旋转动力学的适当描述，而Foldy-Wouthuysen旋转操作员更适合在强场上进行。
A relativistic spin operator cannot be uniquely defined within relativistic quantum mechanics. Previously, different proper relativistic spin operators have been proposed, such as spin operators of the Foldy-Wouthuysen and Pryce type, that both commute with the free-particle Dirac Hamiltonian and represent constants of motion. Here we consider the dynamics of a relativistic electron spin in an external electromagnetic field. We use two different Hamiltonians to derive the corresponding spin dynamics. These two are: (a) the Dirac Hamiltonian in presence of an external field, (b) the semirelativistic expansion of the same. Considering the Foldy-Wouthuysen and Pryce spin operators we show that these lead to different spin dynamics in an external electromagnetic field, which offers possibilities to distinguish their action. We find that the dynamics of both spin operators involve spin-dependent and spin-independent terms, however, the Foldy-Wouthuysen spin dynamics additionally accounts for the relativistic particle-antiparticle coupling. We conclude that the Pryce spin operator provides a suitable description of the relativistic spin dynamics in a weak-to-intermediate external field, whereas the Foldy-Wouthuysen spin operator is more suitable in the strong field regime.
