How to fold a spin chain: Integrable boundaries of the Heisenberg XXX   and Inozemtsev hyperbolic models
  We present a general method of folding an integrable spin chain, defined on a line, to obtain an integrable open spin chain, defined on a half-line. We illustrate our method through two fundamental models with sl(2) Lie algebra symmetry: the Heisenberg XXX and the Inozemtsev hyperbolic spin chains. We obtain new long-range boundary Hamiltonians and demonstrate that they exhibit Yangian symmetries, thus ensuring integrability of the models we obtain. The method presented provides a "bottom-up" approach for constructing integrable boundaries and can be applied to any spin chain model. 
Alejandro De La Rosa Gomez, Niall MacKay, Vidas Regelskis
math-ph hep-th math.MP nlin.SI