| The two-dimensional CuO layers of high temperature superconducting Cuprates (HTSC) are believed to be the playground of the superconducting (SC) coupling. However, at least in the theoretical description, three dimensions are necessary for the establishment of a symmetry broken phase at finite temperature. Moreover, experiments show that the superconducting transition temperature increases with the number of layers. In this work, we employ the Variational Cluster Approach (VCA) to study the phase diagram of the 2D repulsive bilayer (?) Hubbard model. Our results show a strong renormalisation of the interlayer hopping in the superconducting phase: The splitting in the spectra, which is caused by the interlayer hopping, is reduced by 50% when going from the normal phase to the superconducting phase. This reduction is much less than what obtained in photoemission experiment [Feng, 2001] We discuss prelimiary results obtained by using bath sites which are expected to provide a better description of charge dynamics away from half filling. |
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