On a class of non-self-adjoint periodic eigenproblems with boundary and interior singularities

Abstract

We prove that the spectrum of a certain PT-symmetric periodic problem is purely real. Our results extend to a larger class of potentials those recently found by Brian Davies [math.SP/0702122] and John Weir [arXiv:0711.1371].

20 pages, this final version includes correction of several typos and change of title