We derive the solutions of the boundary Yang-Baxter equation associated with a supersymmetric nineteen vertex model constructed from the three-dimensional representation of the twisted quantum affine Lie superalgebra U q [osp (2|2) (2) ]U q [C (2) (2) ]. We found three classes of solutions. The type I solution is characterized by three boundary free-parameters and all elements of the corresponding reflection K-matrix are different from zero. In the type II solution, the reflection K-matrix is even (every element of the K-matrix with an odd parity is null) and it has only one boundary free-parameter. Finally, the type III solution corresponds to a diagonal reflection K-matrix with two boundary free-parameters.
The modelThis letter concerns with the reflection K-matrices of a supersymmetric nineteen vertex model introduced by Yang and Zhang in [1] (see also [2][3][4][5]). The Yang-Zhang R-matrix is constructed from a three-dimensional representation V of the twisted quantum affine Lie superalgebra(2) ], and the periodic algebraic Bethe Ansatz of this vertex model was performed in [6].Vertex models with underlying symmetries corresponding to Lie superalgebras are important in several fields of physics and mathematics. For instance, Z 2 -graded Lie superalgebras appear in the study of lattice models of strongly correlated electrons, such as the supersymmetric generalizations of the t-J model [7][8][9][10][11] and the Hubbard model [12,13], among others. The integrability of supersymmetric two-dimensional quantum chains had proved to be important as well in the AdS/CFT correspondence, either in the N = 4 super Yang-Mills side of the duality [14][15][16], or in the AdS 5 × S 5 string theory side [17]. Furthermore, these mathematical structures also are important in the construction of supersymmetric Hopf algebras and quantum groups [18][19][20][21] [30]. Considering now nonperiodic boundary conditions, the diagonal K-matrices for the ZFvm were first derived in [31] and the general Kmatrices were deduced in [32] and [33]; for the IKvm, the diagonal K-matrices were found in [34] and the general K-matrices were derived in [33] and [35]; besides, the coordinate Bethe Ansätze for both models were presented in [36], while their algebraic versions were performed in [37] (although the ZFvm had been considered before in [31] with the help of the fusion procedure [26]). Among the ZFvm and IKvm, other nineteen vertex models were discovered since then, for instance, the supersymmetric vertex models associated with the sl (2|1) and osp (2|1) Lie superalgebras, whose R-matrix was presented in [38] and the corresponding reflection K-matrices were obtained in [33]; for the Bethe Ansätze of these models, see [36,39]. Finally, other more complex nineteen vertex models were also discovered in the last decade − see, for instance, [40][41][42][43][44][45].The supersymmetric nineteen vertex model which we consider here is not included in the list above. The Rmatrix associated with this model was constructed in [1] and it can be wri...