Spin polarons and molecules in strongly-interacting atomic Fermi gases
  We examine pairing and molecule formation in strongly-interacting Fermi gases, and we discuss how radio-frequency (RF) spectroscopy can reveal these features.   For the balanced case, the emergence of stable molecules in the BEC regime results in a two-peak structure in the RF spectrum with clearly visible medium effects on the low-energy part of the molecular wavefunction.   For the highly-imbalanced case, we show the existence of a well-defined quasiparticle (a spin polaron) on both sides of the Feshbach resonance, we evaluate its lifetime, and we illustrate how its energy may be measured by RF spectroscopy. 
P. Massignan, G. M. Bruun, H. T. C. Stoof