Abstract
Peccei–Quinn (PQ) mechanism based on a chiral global U(1) symmetry is considered to be a simple and elegant solution for strong CP problem. The fact that the mechanism could be experimentally examined through the axion search makes it much more interesting and recently it causes a lot of attention again. However, it is also known that the mechanism is annoyed by two serious problems, that is, a domain wall problem and goodness of global symmetry. Any global symmetry is considered not to be exact due to the quantum effect of gravity. In this paper, we consider a solution to these problems, in which quark mass hierarchy and mixing, neutrino mass generation and existence of dark matter are closely related. In our solution, PQ symmetry is assumed to be induced through symmetry breaking at an intermediate scale of a local U(1) symmetry, and a global U(1) symmetry which plays a role of Froggatt–Nielsen symmetry . In the lepton sector, a remnant of the PQ symmetry controls neutrino mass generation and dark matter existence.
Highlights
Strong C P problem is one of serious problems in the standard model (SM), which is suggested by an experimental bound of the electric dipole moment of a neutron [1,2,3]
We have proposed a model which could solve the strong C P problem based on the PQ mechanism
We introduce a local U (1)g symmetry and a flavor dependent global U (1)F N symmetry
Summary
Strong C P problem is one of serious problems in the standard model (SM), which is suggested by an experimental bound of the electric dipole moment of a neutron [1,2,3]. We assume that the axion energy density coming from the domain wall decay is subdominant and NDW = 1 could be a solution for the strong C P problem. Since the axion could not be a dominant component of DM in this scenario as discussed above, we need to prepare a candidate for the DM For this purpose, the leptonic sector is extended by an additional doublet scalar η and three right-handed neutrinos Ni so as to realize the scotogenic model [57,65,66,67,68,69,70,71,72]. After the symmetry breaking due to σ , U (1)P Q invariant operators are considered to be generated in both Yukawa couplings and scalar potential of an effective theory at energy regions below σ. One should note that it is a crucial element of the neutrino mass generation in the original scotogenic model
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