An integrable eight-state supersymmetric
U model is proposed, which is a fermion model with correlated single-particle and pair hoppings as well as uncorrelated triple-particle hopping. It has a
gl(3∣1) supersymmetry and contains one symmetry-preserving free parameter. The model is solved and the Bethe ansatz equations are obtained.
A detailed study of a model for strongly-interacting fermions with exclusion rules and lattice
N=2 supersymmetry is presented. A submanifold in the space of parameters of the model where it is Bethe-ansatz solvable is identified. The relation between this manifold and the existence of additional, so-called dynamic, supersymmetries is discussed. The ground states are analysed with the help of cohomology techniques, and their exact finite-size Bethe roots are found. Moreover, through analytical and numerical studies it is argued that the model provides a lattice version of the
N=1 super-sine-Gordon model at a particular coupling where an additional
N=(2,2) supersymmetry is present. The dynamic supersymmetry is shown to allow an exact determination of the gap scaling function of the model.