I was given a problem by my professor, which belongs to Migdal. The problem is as follows:
If a particle is rotated by 2$\pi$ in a magnetic field its wave-function $\psi$ transforms into $\exp(i\phi A) \psi$, where $\phi$ is given by the perimeter of the circle, while if the field were that of a strong force, $\phi$ is given by the area of the circle.
Can anybody refer me to the paper where all these are calculated? I'll appreciate your answers.
However, just explaining why $\psi$ transforms into $\exp(i\phi A) \psi$, will be a great help (suppose the case of magnetic field).