Prof Yupeng Wang
Director, Institute of Physics, Chinese Academy of Sciences, Beijing, China

A systematic Bethe ansatz method will be introduced for the integrable models without U(1) symmetry, which can not be solved by the conventional Bethe ansatz methods because of the lack of a proper "local vacuum". By constructing the operator product identities of the transfer matrix, an extended T-Q relation, which could be universal for most integrable models, is observed. As examples, the exact solutions of the XXZ spin torus, the spin chains with arbitrary boundary fields and the XYZ model with odd number of sites are derived.