G. Vodev, ASYMPTOTICS ON THE NUMBER OF SCATTERING POLES FOR DEGENERATE PERTURBATIONS OF THE LAPLACIAN, Journal of functional analysis, 138(2), 1996, pp. 295-310
For a class of compactly supported hypoelliptic perturbations of the L
aplacian in R(n), n greater than or equal to 3 odd, we prove that an a
symptotic on the number of the eigenvalues of the corresponding refere
nce operator implies a similar asymptotic for the number of the scatte
ring poles. (C) 1996 Academic Press, Inc.