THEORY OF SEPARATION PHENOMENA IN STRONGLY-CORRELATED ELECTRON-SYSTEMS

We present a coherent gauge-theoretical interpretation of various poss ible separation phenomena of strongly-correlated electron systems. The typical examples are (i) charge-spin separation (CSS) in the t-J mode l of high-Tc superconductivity, and (ii) particle-flux separation (PFS ) in the quantum Ball effect at nu=1/2. By introducing auxiliary gauge fields, we map the system into an effective U(1) lattice gauge theory . It exhibits a confinement-deconfinement (CD) phase transition at T-C D At T >T-CD, the system is in a confinement phase and the electrons t hemselves are quasiparticles. At T <T-CD, the system is in a deconfine ment phase and each constituent degrees of freedoms of electrons (holo ns and spinons in CSS and composite fermions and fluxes in PFS) are li berated and become independent quasiparticles.