Electroweak baryogenesis and dark matter from a singlet Higgs

Abstract

Abstract. If the Higgs boson H couples to a singlet scalar S via λ m |H| 2 S 2 , a strong electroweak phase transition can be induced through a large potential barrier that exists already at zero temperature. In this case properties of the phase transition can be computed analytically. We show that electroweak baryogenesis can be achieved using CP violation from a dimension-6 operator that couples S to the top-quark mass, suppressed by a new physics scale that can be well above 1 TeV. Moreover the singlet is a dark matter candidate whose relic density is 3% of the total dark matter density, 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.

Effects of two inert scalar doublets on Higgs boson interactions and the electroweak phase transition

“…We remark that due to the absence of a CP-violating phase in the potential V an additional source of CP violation has to be included in the Lagrangian of the more complete theory for it to be realistic for baryogensis. One possibility is to introduce dimension-six operators which couple the inert scalars to the top-quark mass and are suppressed by a new-physics scale that can be well above one TeV, in analogy to a scenario of electroweak baryogenesis from a singlet scalar [60].…”

Gravitational waves from the first order electroweak phase transition in the Z3 symmetric singlet scalar model

“…[10,11]. In another implementation imposing unbroken discrete symmetry like Z 2 [7,[12][13][14][15][16], multi-step PT could utilize a tree level barrier. But generically the absence of mixing renders the tests at colliders difficult without taking enough large λ sh coupling as discussed in Refs.…”

“…The mechanism to generate a thermal cubic term for h by a tree level barrier is most easily implemented in the extended Higgs sectors by a singlet S , containing effective tree-level cubic terms ∼ S 3 + S |H| 2 with H the SM Higgs doublet [5][6][7][8][9][10][11]. If the extended Higgs sector respects some symmetry such as Z 2 , under which S → −S and H → H, an alternative way to the desired tree level barrier is available in the symmetric limit where S does not acquire VEV at the present universe [7,[12][13][14][15][16]. Such a scenario is associated with multi-step PT's.…”

Gravitational waves from the first order electroweak phase transition in the$ Z_{3}$ symmetric singlet scalar model

“…In this case, the thermal relic density of the model which is normalized by the observed one Ω DM h 2 = 0.1199 ± 0.0022 [29] is predicted as Ω s /Ω DM ≃ 10 −2 . However, just like in the Z 2 model, it fails, at least being the dominant DM component because the relic density is suppressed owing to the large singlet-Higgs coupling required by SFOEWPT [12,13]. Here the presence of a new coupling A s still does not open the region λ sh ≲ O(0.01) that is necessary to accommodate correct DM relic density.…”