Generalized T–Q relations and the open XXZ chain

Abstract

We propose a generalization of the BaxterT–Q relation which involves more than one independentQ(u). We argue that the eigenvalues of the transfer matrix of theopen XXZ quantum spin chain are given by such generalizedT–Q relations, for the case that at most two of the boundary parameters{α−, α+, β−, β+} are nonzero, and the bulk anisotropy parameter has valuesη = iπ/2, iπ/4, ....