  The quantum fluctuations of the Higgs field during inflation could be a
source of primordial density perturbations through Higgs-dependent inflaton
decay. By measuring primordial non-Gaussianities, this so-called
Higgs-modulated reheating scenario provides us a unique chance to probe Higgs
interactions at extremely high energy scale, which we call the Cosmological
Higgs Collider (CHC). We realize CHC in a simple scenario where the inflaton
decays into Higgs-portal scalars, taking account of the decay of the Higgs
fluctuation amplitude after inflation. We also calculate the CHC signals of
Standard Model particles, namely their imprints in the squeezed bispectrum,
which can be naturally large. The concept of CHC can be straightforwardly
generalized to cosmological isocurvature colliders with other types of
isocurvature perturbations.
