Finite size properties of staggered Uq[sl(2|1)] superspin chains

Based on the exact solution of the eigenvalue problem for the Uq[sl(2|1)] vertex model built from alternating three-dimensional fundamental and dual representations by means of the algebraic Bethe ansatz we investigate the ground state and low energy excitations of the corresponding mixed superspin chain for deformation parameter q=exp(-iγ/2). The model has a line of critical points with central charge c=0 and continua of conformal dimensions grouped into sectors with γ-dependent lower edges for 0≤γ<π/2. The finite size scaling behavior is consistent with a low energy effective theory consisting of one compact and one non-compact bosonic degree of freedom. In the 'ferromagnetic' regime π<γ≤2π the critical theory has c=-1 with exponents varying continuously with the deformation parameter. Spin and charge degrees of freedom are separated in the finite size spectrum which coincides with that of the Uq[osp(2|2)] spin chain. In the intermediate regime π/2<γ<π the finite size scaling of the ground state energy depends on the deformation parameter.