Exact solution of an su(n) spin torus
  The trigonometric su(n) spin chain with anti-periodic boundary condition (su(n) spin torus) is demonstrated to be Yang-Baxter integrable. Based on some intrinsic properties of the R-matrix, certain operator product identities of the transfer matrix are derived. These identities and the asymptotic behavior of the transfer matrix together allow us to obtain the exact eigenvalues in terms of an inhomogeneous T-Q relation via the off-diagonal Bethe Ansatz. 
Kun Hao, Junpeng Cao, Guang-Liang Li, Wen-Li Yang, Kangjie Shi and   Yupeng Wang
math-ph cond-mat.stat-mech hep-th math.MP