Alexandre Eremenko, Andrei Gabrielov
We describe a parametrization of the real spectral locus of the two-parametric family of PT-symmetric quartic oscillators. For this family, we find a parameter region where all eigenvalues are real, extending the results of Dorey, Dunning, Tateo and Shin.
http://arxiv.org/abs/1105.2742
Mathematical Physics (math-ph)