Theory of resonant inelastic X-ray scattering in cuprates

We analyze theoretically resonant inelastic X-ray scattering near the Cu absorption K edge in some cuprates (La2CuO4, Sr2CuO3, SrCuO2). We explain the drastic momentum dependence of the spectra observed recently in experiments. The antiferromagnetic ground state is described by using the Hartree-Fock approximation, and scattering by the Cu1s core hole is treated within the Born approximation, and the electron correlation effects are taken into account within the random phase approximation, using the time-dependent perturbation theory. The main spectral weight originates predominantly from the charge transfer process. The electron correlations between Cu3d electrons are essential for the drastic momentum dependence.