The Hubbard chain: Lieb-Wu equations and norm of the eigenfunctions

We conjecture that the square of the norm of the Hubbard wave function is p roportional to the determinant of a matrix, which is obtained by linearizat ion of the Lieb-Wu equations around a solution. This means that in the vici nity of a solution the Lieb-Wu equations are non-degenerate, if the corresp onding wave function is non-zero. We further derive an action that generate s the Lieb-Wu equations and express our determinant formula for the square of the norm in terms of the Hessian determinant of this action. (C) 1999 Pu blished by Elsevier Science B.V. All rights reserved.