Symmetries of Strongly Correlated Electrons
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Strongly correlated electronic systems are believed to be of great importance in relation with high-T c superconductivity. In the very center of attention are the two-dimensional Hubbard and t-J models. It is a very interesting fact that both these models are exactly solvable by Bethe Ansatz in one spatial dimension (the t-J model only at the supersymmetric point J = ±2t). There are indications that the two-dimensional models share important features with their one-dimensional analogs. One of the many puzzling problems of strongly correlated electronic systems in one and two dimensions is the question of separation of spin and charge degrees of freedom. In this talk we discuss the importance of symmetries for systems of correlated electrons. We show that both the excitation spectrum over the half-filled ground state and exact Scattering matrix of the Hubbard model are determined by the SO(4) symmetry of the Hubbard hamiltonian. We find that quasiparticles separate into spinless charge-carriers and chargeless spin-carriers, which very nicely and precisely reflets the spin- and charge separation at half filling.
KeywordsExcitation Spectrum Hubbard Model Symmetry Algebra HEISENBERG Chain Quasi Particle
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