Symmetry analysis of ARPES and EELS: Probing the standard model of HTSC

Roland Hayn

Faculté de Sciences de Saint Jerome, L2MP, 13397 Marseille Cedex 20, France

Band structure results, cluster calculations and symmetry arguments are used to analyze polarization dependent angle resolved photoemission (ARPES) data, as well as electron energy loss spectra (EELS) of undoped cuprates. The oxygen-2-pi states are shown to play an important role, in addition to the Zhang-Rice singlet excitations, in order to understand the different spectra. However, for ARPES both types of excitations are well separated energetically and in momentum space, whereas they are nearly degenerate and determine the character of the charge transfer gap in EELS.