  We formulate a wilsonian renormalization group theory for the imbalanced
Fermi gas. The theory is able to recover quantitatively well-established
results in both the weak-coupling and the strong-coupling (unitarity) limit. We
determine for the latter case the line of second-order phase transitions of the
imbalanced Fermi gas and in particular the location of the tricritical point.
We obtain good agreement with the recent experiments of Y. Shin {\it et al}.
[Nature {\bf 451}, 689 (2008)].
