Das Konsistenzproblem der Greenfunktion eines A-Hyperons in Kernmaterie

An iteration procedure is derived for determining a self-consistent approximation for the one-particle Green's function in any order, starting from perturbation theory. This method is used to calculate the second Born approximation of the self energy of a Λ-particle in nuclear matter. After one iteration the approximation is nearly self-consistent. The value of the binding energy of the Λ-paiticle is only slightly decreased from the value of perturbation theory. Because of the vanishing particle density of the Λ-hyperon the quasiparticle energy depends on the square of the momentumk, the width of the spectral function is proportional tok ⁴ and the imaginary part of the self energy operator is proportional to (Ω-μ)^5/2 for Ω approaching the chemical potential μ.