  We calculate the inelastic lifetime of an electron quasiparticle due to
Coulomb interactions in an electron liquid at low (or zero) temperature in two
and three spatial dimensions. The contribution of "exchange" processes is
calculated analytically and is shown to be non-negligible even in the
high-density limit in two dimensions. Exchange effects must therefore be taken
into account in a quantitive comparison between theory and experiment. The
derivation in the two-dimensional case is presented in detail in order to
clarify the origin of the disagreements that exist among the results of
previous calculations, even the ones that only took into account "direct"
processes.
