Dark CP violation and gauged lepton or baryon number for electroweak baryogenesis

Abstract

We explore the generation of the baryon asymmetry in an extension of the standard model where the lepton number is promoted to a Uð1Þ l gauge symmetry with an associated Z 0 gauge boson. This is based on a novel electroweak baryogenesis mechanism first proposed by us in Ref. [M. Carena, M. Quiros, and Y. Zhang, Electroweak Baryogenesis From Dark CP violation, Phys. Rev. Lett. 122, 201802 (2019).]. Extra fermionic degrees of freedom, including a fermionic dark matter χ, are introduced in the dark sector for anomaly cancellation. The lepton number is spontaneously broken at high scale and the effective theory, containing the standard model, the Z 0 , the fermionic dark matter, and an additional complex scalar field S, violates CP in the dark sector. The complex scalar field couples to the Higgs portal and is essential in enabling a strong first order phase transition. Dark CP violation is diffused in front of the bubble walls and creates a chiral asymmetry for χ, which in turn creates a chemical potential for the standard model leptons. Weak sphalerons are then in charge of transforming the net lepton charge asymmetry into net baryon number. We explore the model phenomenology related to the leptophilic Z 0 , the dark matter candidate, the Higgs boson, and the additional scalar, as well as implications for electric dipole moments. We also discuss the case when baryon number Uð1Þ B is promoted to a gauge symmetry, and discuss electroweak baryogenesis and its corresponding phenomenology.

CP violation from charged Higgs bosons in the three Higgs doublet model

“…(i.e., Higgs-strahlung off b-quarks). 9 Since the Higgs-strahlung cross section is much smaller than the one for top-antitop quark production, a light charged Higgs boson is severely constrained while direct searches for a heavy one leave it largely unconstrained. However, when M…”

“…we should also compare to the collider limits for H ± 3 → cb and cs. However, these are less 9 Recall that b-(anti)quarks are produced inside protons from a gluon splitting. 10 Comparing the upper and lower left panels of figure 3 shows that the cross section times BR of H ± 2 is essentially unaffected by the mass of the heavier H ± 3 , once it is at least comparable to the top quark mass.…”

“…At the same time, new CP-violating physics with direct couplings to quarks or leptons is becoming increasingly tightly constrained by measurements that set stringent upper limits on the electric dipole moments (EDMs) of the neutron [3] and electron [4]. These improved limits have led particle theorists to consider models in which the additional CP violation is sequestered in a hidden or dark sector that does not couple directly to SM fermions [5][6][7][8][9][10][11].…”

Electric dipole moments, new forces and dark matter

“…For a recent proposal of a mechanism of baryogenesis in theories with gauged baryon or lepton number see refs. [42,43]. A detailed study of the implications of our results for the generation of the matter-antimatter asymmetry is beyond the scope of this letter.…”

The Higgs and leptophobic force at the LHC

“…[13][14][15][16][17], while for a mechanism for baryogenesis in this scenario see ref. [18]. The coupling between the SM quarks and Z B in our convention is given by…”