AI 中文总结
研究存在恒定均匀磁场时量子电动力学中费米子 - 光子顶点，计算到一圈阶，分析其结构变化，专注纯横向反常磁矩分量，找到跃迁选择规则，发现振幅特性及禁戒跃迁情况，还表明计算允许跃迁时无需光子质量。
AI 中文摘要
我们计算了在恒定均匀磁场存在下量子电动力学中费米子 - 光子顶点到一圈阶。表明即使在树图水平顶点也因磁场导致的洛伦兹不变性丧失而改变，分裂为纵向和横向部分。辐射修正诱导出丰富张量结构，包括横向、平行及混合横向/平行方向的反常磁矩。我们专注研究纯横向方向的反常磁矩分量，找到几个低阶朗道能级间跃迁的选择规则，发现由于磁场导致的时间反演不变性丧失，从初态到终态朗道能级跃迁的振幅与反向过程相差一个符号。与真空情况相反，振幅通常是复数，相位因子可解释为衰变态的有限寿命。对于纯横向方向的反常磁矩，占据最低两个朗道能级的态之间的跃迁是禁戒的。此外，对于允许跃迁的计算，我们发现由于磁场起到红外调节器的作用，无需包含光子质量。
英文摘要
We compute the fermion-photon vertex in QED in the presence of a constant and uniform magnetic background up to one-loop order. We show that even at tree-level, the vertex is modified due to the loss of Lorentz invariance induced by the magnetic field, thus breaking into longitudinal and transverse pieces. Moreover, the radiative corrections induce the emergence of a rich tensor structure that includes the anomalous magnetic moments in the transverse, parallel, and mixed transverse/parallel directions. We concentrate on studying one of these anomalous magnetic moment components, the one in the purely transverse direction. We find the selection rules for transitions between a few low-lying Landau levels and show that the amplitudes for transitions from an initial to a final Landau level differ by a sign from the reverse process due to the loss of time reversal invariance induced by the presence of the field. Contrary to the vacuum case, the amplitudes are, in general, complex, and the phase factor can be interpreted in terms of a finite life-time of the decaying state. For the anomalous magnetic moment in the purely transverse direction, transitions between states occupying both the lowest Landau levels are forbidden. Moreover, for the computation of the allowed transitions, we find that it is not necessary to include a photon mass since the magnetic field acts as an infrared regulator.
