COMPLETE PSEUDOHOLE AND HEAVY-PSEUDOPARTICLE OPERATOR REPRESENTATION FOR THE HUBBARD CHAIN

We introduce the pseudohole and heavy-pseudoparticle operator algebra that generates all Hubbard-chain eigenstates from a single reference v acuum. In addition to the pseudoholes already introduced for the descr iption of the low-energy physics, this involves the heavy pseudopartic les associated with Hamiltonian eigenstates whose energy spectrum has a gap relative to-the many-electron ground state. We introduce a gener alized pseudoparticle perturbation theory that describes the relevant finite-energy ground-state transitions. In the present basis these exc itations refer to a small density of excited pseudoparticles. Our oper ator basis goes beyond the Bethe-ansatz solution and it is the suitabl e and correct starting point for the study of the finite-frequency pro perties, which are of great relevance for the understanding of the unu sual spectral properties detected in low-dimensional novel materials.