Exceptional points for associated Legendre functions of the second kind
Abstract
We consider the complex plane structure of the associated Legendre function of the second kind . We find that for any noninteger value for has an infinite number of poles in the complex plane, but for any negative integer there are no poles at all. For or any positive integer there is only a finite number of poles, with there only being one single pole (at ) when . This pattern is characteristic of the exceptional points that appear in a wide variety of physical contexts. However, unusually for theories with exceptional points, has an infinite number of them. Other than in the -symmetry Jordan-block case, exceptional points usually occur at complex values of parameters. While not being Jordan-block exceptional points themselves, the exceptional points associated with the nonetheless occur at real values of .
Cite
@article{arxiv.2301.04092,
title = {Exceptional points for associated Legendre functions of the second kind},
author = {Tianye Liu and Daniel A. Norman and Philip D. Mannheim},
journal= {arXiv preprint arXiv:2301.04092},
year = {2023}
}
Comments
6 pages