Interference effects and the use of Higgs boson pair production to study the Higgs trilinear self coupling

We show that the dominant channel proposed for the determination of the Higgs boson trilinear coupling, $pp\to HH+X$ via gluon fusion, exhibits an interference structure that is independent of the collider energy for collider energies in the range $8\mathrm{T}\mathrm{e}\mathrm{V}\le \sqrt{s}\le 100\mathrm{T}\mathrm{e}\mathrm{V}$ and is almost maximally destructive. This insensitivity to the collider energy remains approximately true for a variety of other two Higgs production mechanisms although the magnitude of the interference varies widely.