Electroweak baryogenesis and dark matter from a singlet Higgs

Abstract

If the Higgs boson H couples to a singlet scalar S via λm|H|2S2, a strong electroweak phase transition can be inducedthrough a large potential barrier that exists already at zerotemperature. In this case properties of the phase transition can becomputed analytically. We show that electroweak baryogenesis can beachieved using CP violation from a dimension-6 operator that couplesS to the top-quark mass, suppressed by a new physics scale that canbe well above 1 TeV. Moreover the singlet is a dark matter candidatewhose relic density is ≲3% of the total dark matterdensity, but which nevertheless interacts strongly enough with nuclei(through Higgs exchange) to be just below the current XENON100 limits.The DM mass is predicted to be in the range 80–160 GeV.