Dynamic Structure Factor of the Two-Dimensional Shastry-Sutherland Model

We calculate the 2-triplon contribution to the dynamic structure factor of the 2-dimensional Shastry-Sutherland model, realized in SrCu2(BO3)2, by means of perturbative continuous unitary transformations. For realistic parameters we find flat bound 2-triplon bands. These bands show large weight in the structure factor depending strongly on momentum. So our findings permit a quantitative understanding of high precision inelastic neutron scattering experiments.