Acoustic plasmons and doping evolution of Mott physics in resonant inelastic x-ray scattering from cuprate superconductors

By incorporating a long-range Coulomb interaction into the framework of the one-band Hubbard model, we delineate how the low-energy plasmon around 1 eV, which is a universal feature of the charge dynamics of the cuprates, manifests itself in the resonant inelastic x-ray scattering (RIXS) spectra. The long-range Coulomb interaction in the doped system controls the form of the intraband RIXS dispersion near the Brillouin zone center around the Gamma point. The out-of-plane momentum transfer component q(z) is found to play a key role in determining whether or not the RIXS spectrum shows a plasmon-related gap at Gamma.