  We perform the spectral analysis of a zero temperature Pauli-Fierz system for
small coupling constants. Under the hypothesis of Fermi golden rule, we show
that the embedded eigenvalues of the uncoupled system disappear and establish a
limiting absorption principle above this level of energy. We rely on a positive
commutator approach introduced by Skibsted and pursued by
Georgescu-Gerard-Moller. We complete some results obtained so far by
Derezinski-Jaksic on one side and by Bach-Froehlich-Segal-Soffer on the other
side.
