  We consider a recent momentum-resolved radio-frequency spectroscopy
experiment, in which Fermi liquid properties of a strongly interacting atomic
Fermi gas were studied. Here we show that by extending the Brueckner-Goldstone
model, we can formulate a theory that goes beyond basic mean-field theories and
that can be used for studying spectroscopies of dilute atomic gases in the
strongly interacting regime. The model hosts well-defined quasiparticles and
works across a wide range of temperatures and interaction strengths. The theory
provides excellent qualitative agreement with the experiment. Comparing the
predictions of the present theory with the mean-field Bardeen-Cooper-Schrieffer
theory yields insights into the role of pair correlations, Tan's contact, and
the Hartree mean-field energy shift.
