Non linear pseudo-bosons versus hidden Hermiticity. II: The case of   unbounded operators
  Parallels between the notions of nonlinear pseudobosons and of an apparent non-Hermiticity of observables as shown in paper I (arXiv: 1109.0605) are demonstrated to survive the transition to the quantum models based on the use of unbounded metric in the Hilbert space of states. 
Fabio Bagarello and Miloslav Znojil
math-ph math.MP quant-ph