PT symmetry breaking and explicit expressions for the pseudo-norm in the   Scarf II potential
  Closed expressions are derived for the pseudo-norm, norm and orthogonality relations for arbitrary bound states of the PT symmetric and the Hermitian Scarf II potential for the first time. The pseudo-norm is found to have indefinite sign in general. Some aspects of the spontaneous breakdown of PT symmetry are analysed. 
G. Levai, F. Cannata and A. Ventura