Higgs inflation: particle factory

A bstract We study cosmological gravitational particle production (CGPP) in Higgs inflation, wherein the inflaton is a scalar field with quartic self-coupling λ and a nonminimal coupling to gravity ξ , and which may, but need not be, the Higgs boson of the Standard Model (SM). We find an explosive particle production peaked on a characteristic comoving wavenumber k ~ ξ 2 / 3 aH with a peak occupation number that scales with ξ . This new peak in production can easily dominate over the conventional (minimally coupled inflation) CGPP even for modest values of ξ . The results apply for a wide range of ξ , e.g., as low as ξ = 10, which can be realized for the Standard Model Higgs given suitable RG flow of the quartic coupling. We discuss implications for late time relics such as dark matter.