Abstract :
The integrable XXX spin s quantum chain and the alternating s1, s2 (s1−s2=1/2) chain with boundaries are considered. The scattering of their excitations with the boundaries via the Bethe ansatz method is studied, and the exact boundary S matrices are computed in the limit s,s1,2→∞. Moreover, the connection of these models with the SU(2) Principal Chiral, WZW and the RSOS models is discussed.