Asymptotic behavior of the limiting phase shifts in the case of scattering by a potential without spherical symmetry

Scattering by a potential which decreases at large distances faster than $|x|^{-1}$ is considered. The spectrum of the $S$ matrix at fixed energy is studied. The asymptotic behavior of the eigenvalues at large values of the serial number is obtained. Similar expressions are obtained when allowance is made for an electromagnetic field. The scheme is also applied to the Dirac equation.