Integrable impurities for an open fermion chain

Employing the graded versions of the Yang-Baxter equation and the reflectio n equations, we construct two kinds of integrable impurities for a small-po laron model with general open boundary conditions: (a) we shift the spectra l parameter of the local Lax operator at arbitrary sites in the bulk and (b ) we embed the impurity fermion vertex at each boundary of the chain. The H amiltonians with different types of impurity terms are given explicitly. Th e Bethe ansatz equations, as well as the eigenvalues of the Hamiltonians, a re constructed by means of the quantum inverse scattering method. In additi on, we discuss the ground-state properties in the thermodynamic limit.