  ARPES spectra hold a wealth of information about the many-body interactions
in a correlated material. However, the quantitative analysis of ARPES spectra
to extract the various coupling parameters in a consistent manner is extremely
challenging, even for a model Fermi liquid system. We propose a fitting
procedure which allows quantitative access to the intrinsic lineshape,
deconvolved of energy and momentum resolution effects, of the correlated
2-dimensional material Sr2RuO4. For the first time in correlated 2-dimensional
materials, we find an ARPES linewidth that is narrower than its binding energy,
a key property of quasiparticles within Fermi liquid theory. We also find that
when the electron-electron scattering component is separated from the
electron-phonon and impurity scattering terms it decreases with a functional
form compatible with Fermi liquid theory as the Fermi energy is approached. In
combination with the previously determined Fermi surface, these results give
the first complete picture of a Fermi liquid system via ARPES. Furthermore, we
show that the magnitude of the extracted imaginary part of the self-energy is
in remarkable agreement with DC transport measurements.
