Nested algebraic Bethe ansatz for deformed orthogonal and symplectic spin chains

Abstract

We construct exact eigenvectors and eigenvalues for Uq(sp2n)- and Uq(so2n)-symmetric closed spin chains by means of a nested algebraic Bethe ansatz method. We use a fusion procedure to construct higher-dimensional Lax operators. Our approach generalises and extends the results obtained by Reshetikhin and De Vega–Karowski. We also present a generalisation of Tarasov–Varchenko trace formula for nested Bethe vectors.