Evgeny Korotyaev and Oleg Safronov
Eigenvalue bounds for Stark operators with complex potentials
(563K, pdf)

ABSTRACT.  We consider the 3-dimensional Stark operator perturbed by a complex-valued potential. 
We obtain an estimate for the number of eigenvalues of this operator as well as for the sum of imaginary parts of eigenvalues situated in the upper half-plane.