Corrections to the electron-spin magnetic moment near mirrors

This problem has a long history of confusion and error. One crucial question is whether the leading correction δμ/μ is of order α/mL or α/(mL)2, where L is the distance from or between the mirrors. For a particle of infinite mass but finite μ, δμ/μ is of order α/(μL)2 in the weak field limit B → 0. The same is true in quantum mechanics and remains true for a (non-second-quantized) Dirac electron. (orig.)