X-ray absorption in strong correlated high T_C superconductors

In X-ray absorption spectroscopy, a possible process is to create a core hole an add the electron to the valence states. Theoretically, this can be treated by evaluating the one-particle Green's function in the presence of a strong potential. When modelling the antiferromagnetic parent state of high-T_C cuprate superconductors, the potential can be onsite or situated between two neighboring sites. We analyze this problem for parameter regimes relevant to cuprates and iridates using the self-consistent Born approximation.