Radio Frequency Spectroscopy of Trapped Fermi Gases with Population Imbalance

Motivated by recent experiments, we address, in a fully self consistent fashion, the behavior and evolution of radio frequency (RF) spectra as temperature and polarization are varied in population imbalanced Fermi gases. We discuss a series of scenarios for the experimentally observed zero temperature pseudogap phase and show how present and future RF experiments may help in its elucidation. We conclude that the MIT experiments at the lowest $T$ may well reflect ground state properties, but take issue with their claim that the pairing gap survives up to temperatures of the order of the degeneracy temperature $T_F$ at unitarity.