The abstract of the paper "Asymptotic observables for N-body Stark Hamiltonians"

By Tadayoshi Adachi
Annales de l'Institut Henri Poincare -- Physique Theorique 68 (1998), 247--283.

We prove the existence of some asymptotic observables for N-body Stark Hamiltonians, and study their spectral properties, in particular, their relation to the spectrum of the Hamiltonian H.