On Tzitzeica equation and spectral properties of related Lax operators.

We discuss the Tzitzeica equation and the spectral properties associated with its Lax operator L. We prove that the continuous spectrum of L is rotated with respect to the contour of the Riemann-Hilbert problem with angle π/6. We also show that the poles of the dressing factors and their inverses are discrete eigenvalues of L. [ABSTRACT FROM AUTHOR]