MHD alpha2-dynamo, Squire equation and P T -symmetric interpolation between square well and harmonic oscillator

It is shown that the alpha2-dynamo of magnetohydrodynamics, the hydrodynamic Squire equation as well as an interpolation model of PT-symmetric quantum mechanics are closely related as spectral problems in Krein spaces. For the alpha2-dynamo and the PT-symmetric model the strong similarities are demonstrated with the help of a 2 x 2 operator matrix representation, whereas the Squire equation is reinterpreted as a rescaled and Wick-rotated PT-symmetric problem. Based on recent results on the Squire equation the spectrum of the PT-symmetric interpolation model is analyzed in detail and the Herbst limit is described as spectral singularity. [PUBLICATION ABSTRACT]