Dynamic structure factor of the two-dimensional Shastry-Sutherland model

We calculate the two-triplon contribution to the dynamic structure factor of the two-dimensional Shastry-Sutherland model, realized in SrCu2(BO3)(2), by means of perturbative continuous unitary transformations. For realistic parameters we find flat bound two-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.