Berry Phases with Real Hamiltonians With and Without a Many-body System   as a Background
  We present both the gauge theoretic description and the numerical calculations of the Berry phases with the real eigenstates, involving one with a many-body system as a background and the other with no such background. We demonstrate that for the former the sign of the Berry phase factor for a spin $\f{1}{2}$ particle (hole) coupled to a slow subsystem (phonon) depends on both the strength of electron correlations and the characteristics of the closed paths, unlike the cases for the latter. 
S. P. Hong, H. Doh, and S. H. Suck Salk (Pohang University of Science   and Technology, Korea)