Effects of electronic correlation on x-ray absorption and dichroic spectra at L-2,(3) edge

We present a new theoretical approach to describe x-ray absorption and magnetic circular dichroism spectra in the presence of electron-electron correlation. Our approach provides an unified picture to include correlations in both charged and neutral excitations, namely in direct/inversion photoemission where electrons are removed/added, and photoabsorption where electrons are promoted from core levels to empty states. We apply this approach to the prototypical case of the L-2,(3) edge of 3d transition metals and we show that the inclusion of many-body effects in the core level excitations is essential to reproduce, together with satellite structures in core level photoemission, the observed asymmetric lineshapes in x-ray absorption and dichroic spectra.