L. Bruneau, J. Derezinski
Pauli-Fierz Hamiltonians defined as quadratic forms (revised version)
(337K, Postscript)

ABSTRACT.  We study Pauli-Fierz Hamiltonians---self-adjoint operators describing a small quantum system interacting with a bosonic field. Using quadratic form techniques, we extend the results of Derezinski-Gerard and Gerard about the self-adjointness, the location of the essential spectrum and the existence of a ground state to a large class of Pauli-Fierz Hamiltonians.