  A universal high energy anomaly in the single particle spectral function is
reported in three different families of high temperature superconductors by
using angle-resolved photoemission spectroscopy. As we follow the dispersing
peak of the spectral function from the Fermi energy to the valence band
complex, we find dispersion anomalies marked by two distinctive high energy
scales, E_1=~ 0.38 eV and E_2=~0.8 eV. E_1 marks the energy above which the
dispersion splits into two branches. One is a continuation of the near
parabolic dispersion, albeit with reduced spectral weight, and reaches the
bottom of the band at the gamma point at ~0.5 eV. The other is given by a peak
in the momentum space, nearly independent of energy between E_1 and E_2. Above
E_2, a band-like dispersion re-emerges. We conjecture that these two energies
mark the disintegration of the low energy quasiparticles into a spinon and
holon branch in the high T_c cuprates.
