Family of Affine Quantum Group Invariant Integrable Extensions of   Hubbard Hamiltonian
  We construct the family of spin chain Hamiltonians, which have affine quantum group symmetry. Their eigenvalues coincide with the eigenvalues of the usual spin chain Hamiltonians, but have the degeneracy of levels, corresponding to affine quantum group. The space of states of these spin chains is formed by the tensor product of fully reducible representations of quantum group. The fermionic representations of constructed spin chain Hamiltonians show that we have new extensions of Hubbard Hamiltonians. All of them are integrable and have affine quantum group symmetry. The exact ground state of a such type model is presented, exhibiting superconducting behavior via eta-pairing mechanism. 
A.Avakyan, T.Hakobyan, A.Sedrakyan