Hidden Kondo Effect in a Correlated Electron Chain

We develop a general Bethe ansatz formalism for diagonalizing an integrable model of a magnetic impurity of arbitrary spin coupled ferro- or antiferromagnetically to a chain of interacting electrons. The method is applied to an open chain, with the exact solution revealing the existence of a ``hidden'' Kondo effect driven by forward electron scattering off the impurity. We argue that the so-called ``operator reflection matrices'' proposed in recent Bethe ansatz studies of related models emulate only forward electron-impurity scattering, which may explain the absence of complete Kondo screening for certain values of the impurity-electron coupling in these models.