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The structure of edge states in general finite antiferromagnetic quantum spin chains with arbitrary spin value S is discussed within the framework of the nonlinear-sigma model (NL) plus a topological term. Based on a large-N theory of SU (N) quantum antiferromagnets and strong-coupling expansion, we argue that edge states with fractionalized spin quantum number S' exist in all spin chains with S1, with S'=S/2 for integer spin chains and S'= (S-1/2) /2 for half-integer spin chains.
Tai-Kai Ng (Fri,) studied this question.