  We present a three-band Hubbard Hamiltonian and the associated Cu K-edge RIXS
spectra for electron and hole doped cuprates over a wide range of energy and
momentum transfers. By comparing computed spectra for the unfilled case with
the corresponding results for 15% electron or hole doping at two different
values of the effective Hubbard parameter U, generic signatures of the collapse
of the magnetic gap and the characteristic momentum dependencies and evolution
of the spectra with doping are identified. Available RIXS data support the gap
collapse scenario for electron doped cuprates, but the situation in hole doped
systems is found to be less clear.
