Second order perturbation theory for embedded eigenvalues
arXiv:1006.5869 · doi:10.1007/s00220-011-1278-x
Abstract
We study second order perturbation theory for embedded eigenvalues of an abstract class of self-adjoint operators. Using an extension of the Mourre theory, under assumptions on the regularity of bound states with respect to a conjugate operator, we prove upper semicontinuity of the point spectrum and establish the Fermi Golden Rule criterion. Our results apply to massless Pauli-Fierz Hamiltonians for arbitrary coupling.
30 pages, 2 figures