Hidden sector effects on double Higgs production near threshold at the LHC

Abstract In this Letter we study a novel effect of a hidden sector coupling to the standard model Higgs boson: an enhancement of the Higgs pair production cross section near threshold due to bound state effects. After summing the ladder contributions of the hidden sector to the effective g g H H coupling, we find the amplitude for gluon–gluon scattering via a Higgs loop. We relate this amplitude to the double Higgs production cross section via the optical theorem. We find that enhancements of the O ( 100 ) for the partonic cross section near the threshold region can be obtained for a hidden sector strongly coupled to the Higgs boson. The corresponding cross section at the LHC can be as large as O ( 10 ) times the SM result for extreme values of the coupling. The detection of such an effect could in principle lead to important information about the hidden sector.