THEOREM ON PSEUDOSPIN AND ETA-PAIRING SUPERCONDUCTIVITY

We present a theorem on total pseudospin as an eigenvalue in a state. The total pseudospin is determined by the summation of the phase facto rs, written in terms of pseudospin operator and number of electrons. W e discuss its relation with eta-pairing superconductivity and ground-s tate energy level ordering of a system with pseudospin symmetry. Final ly as an application of the theorem we show that the ground state of a generalized Hubbard model is superconducting for any electron filling .