Stabilization of impurity states in crossed magnetic and electric fields

It is shown that the renormalizability of the zero-range interaction in the two-dimensional space is always followed by the existence of a bound state, which is not true for odd-dimensional spaces. A renormalization procedure is defined and the exact retarded Green's function for electrons moving in two dimensions and interacting with both crossed magnetic and electric fields and an attractive zero-range interaction is constructed. Imaginary parts of poles of this Green's function determine lifetimes of quasi-bound (resonance) states. It is shown that for some particular parameters the stabilization against decay occurs even for strong electric fields.