  We address the problem of transmission of electrons between two
noninteracting leads through a region where they interact (quantum dot). We use
a model of spinless electrons hopping on a one-dimensional lattice and with an
interaction on a single bond. We show that all the two-particle scattering
states can be found exactly. Comparisons are made with numerical results on the
time evolution of a two-particle wave packet and several interesting features
are found for scattering. For N particles the scattering state is obtained by
perturbation theory. For a dot connected to Fermi seas at different chemical
potentials, we find an expression for the change in the Landauer current
resulting from the interactions on the dot. We end with some comments on the
case of spin-1/2 electrons.
