Boundary energy of the open XXX chain with a non-diagonal boundary term

Abstract

We analyze the ground state of the open spin-1/2 isotropic quantum spin chain with a non-diagonal boundary term using a recently proposed Bethe ansatz solution. As the coefficient of the non-diagonal boundary term tends to zero, the Bethe roots split evenly into two sets: those that remain finite, and those that become infinite. We argue that the former satisfy conventional Bethe equations, while the latter satisfy a generalization of the Richardson-Gaudin equations. We derive an expression for the leading correction to the boundary energy in terms of the boundary parameters.

10 pages, 9 figures; v2: Figs 4 are improved; v3: reference added; v4: erratum added

References in corpus (3)

• Off-diagonal Bethe ansatz and exact solution of a topological spin ring
• Off-diagonal Bethe ansatz solution of the XXX spin-chain with arbitrary boundary conditions
• Heisenberg XXX Model with General Boundaries: Eigenvectors from Algebraic Bethe Ansatz

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• Lattice regularisation of a non-compact boundary conformal field theory
• Entanglement and boundary entropy in quantum spin chains with arbitrary direction of the boundary magnetic fields
• Entanglement entropy in quantum spin chains with broken parity number symmetry
• Thermodynamic limit and boundary energy of the spin-1 Heisenberg chain with non-diagonal boundary fields
• Ground state solutions of inhomogeneous Bethe equations