A high energy 'kink' in the quasiparticle spectrum as evidence of the importance of charge density fluctuations in the mechanism for high temperature superconductivity in cuprates.

It is suggested that kink-like features in the band spectra of quasiparticles of metal oxide cuprates obtained by photoemission spectroscopy at high energies [variant_greek_epsilon]>=0.3 eV may be related to the appearance of collective charge density fluctuations with quasi-acoustic dispersion (acoustic plasmons) which are caused both by the layered crystalline structure of the metal oxide cuprates and by the strong anisotropy of the electron spectra in the plane of two-dimensional CuO2 layers. These charge density fluctuations should play a significant role in the mechanism for high temperature superconductivity by significantly enhancing the critical temperature for the superconducting transition in metal oxide cuprates. [ABSTRACT FROM AUTHOR]