Effects of a boundary field in the Hubbard open chain

Osamu Tsuchiya, Takashi Yamamoto

The boundary effects in the open Hubbard chain with boundary fields are studied. The boundary string solutions of the Bethe ansatz equations that give rise to a wave functions localized at the boundary and exponentially decreasing away from the boundary are provided. In particular, it is shown that the correct ground state of the model at half-filling contains the boundary strings.

Hitoshi Asakawa, Masuo Suzuki

M. Gulácsi, Annette Bussmann‐Holder, A. R. Bishop

Osamu Tsuchiya

Using the method introduced by Grisaru et al , boundary S-matrices for the physical excitations of the open Hubbard chain with boundary fields are studied. In contrast to the open supersymmetric t-J model, the boundary S-matrix for the charge excitations depend on the boundary fields though the boundary fields do not break the spin-SU(2) symmetry.

Tetsuo Deguchi, Rui‐Hong Yue

The Bethe ansatz equations of the 1-D Hubbard model under open boundary conditions are systematically derived by diagonalizing the inhomogeneous transfer matrix of the XXX model with open boundaries. Through the finite-size correction, we obtain the energy spectrum of the open chain and discuss the effects of boundary magnetic fields applied only at the edges of the chain. Several physical implications of the finite-size spectrum are discussed from the viewpoint of the boundary conformal field theories (BCFT); the conformal dimension of the spin excitation is quite sensitive to the boundary magnetic fields, and this sensitivity can be explained in terms of the $π/2$-phase shift of the BCFT. For several limiting cases such as for the half-filling case, the conformal dimensions are explicitly calculated.

Gerald Bedürftig, Holger Frahm