Higgs self-coupling in γγ collisions

To establish the Higgs mechanism experimentally, one has to determine the Higgs self-interaction potential responsible for the electroweak symmetry breaking. This requires a measurement of the trilinear and quadrilinear self-couplings of the Higgs particle, as predicted by the standard model. We propose that the trilinear Higgs self-coupling be measured in the process γγ→HH just above the kinematic threshold of 2MH, where MH is the Higgs mass. Our calculation shows that the statistical sensitivity of the cross section σγγ→HH to the Higgs self-coupling is maximal near the 2MH threshold for MH between 115 and 150 GeV, and is larger than the statistical sensitivities of σe+e→ZHH and σe+e→ννHH to this coupling for 2Ee≤700 GeV