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Zusammenfassung (Englisch)

The utility of a spectral approximation to the quark propagator will be demonstrated, using low-lying eigenmodes of the hermitian Wilson-Dirac matrix, Q = γ₅ M. The investigation is based on a total of 400 full QCD vacuum configurations, with two degenerate flavors of dynamical Wilson fermions at β = 5 .6, at two different sea quark masses. The spectral approach is successful in accessing both the topological charge and disconnected diagrams, as they appear in the η' correlation function. A suitable partial summation technique is proposed that provides sufficient saturation for Tr Q -1, which is a quantity directly related to the topological charge. In the effective mass plot of the η' meson a consistent early plateau formation is achieved, by ground state projecting the connected piece of the propagator.