Fermi surface reconstruction in strongly correlated Fermi systems as a   first order phase transition
  A quantum phase transition in strongly correlated Fermi systems beyond the topological quantum critical point is studied within the Fermi liquid approach. The transition occurs between two topologically equivalent states, each with three sheets of the Fermi surface. One of these states possesses a quasiparticle halo in the quasiparticle momentum distribution $n(p)$, while the other, the hole pocket. The transition is found to be of the first order with respect to both the coupling constant $g$ and the temperature $T$. The phase diagram of the system in the vicinity of this transition is constructed. 
S.S.Pankratov, M.V.Zverev, M.Baldo
cond-mat.str-el