Neutron electric dipole moment in a supersymmetric model with singlet quarks

Abstract

The neutron electric dipole moment is investigated in a supersymmetric electroweak model admitting SU(2) W singlet and Q = −1/3, say D-type, quarks. Significant CP violating phases appear in the coupling between the singlet D-type quarks and the ordinary d-type quarks. Then, through the d-D mixing effects on the squark mass terms the gluino one-loop diagrams provide naturally the contributions ∼ 10 −26 e cm comparable to the current experimental bound on the neutron electric dipole moment. The CP violation in the d-D coupling would also be relevant for the electroweak baryogenesis.

Quark mixings and flavor changing interactions with singlet quarks

“…Then, various novel features arise through the mixing between the ordinary quarks (q = u, d) and the singlet quarks (Q = U, D). The unitarity of Cabibbo-Kobayashi-Maskawa (CKM) matrix within the ordinary quark sector is violated, and the flavor changing neutral currents (FCNC's) appear at the tree-level [2][3][4][5][6][7]. These flavor changing interactions are actually described in terms of the q-Q mixing parameters and the quark masses, as seen in detail in the text.…”

“…Specifically, the CKM unitarity within the ordinary quark sector is violated, and the FCNC's arise both in the gauge and scalar couplings [2][3][4][5][6][7]. We would like to clarify the structures of these flavor changing interactions for the representative bases.…”

“…Then, these scalar FCNC's are expected to provide significant phenomenological effects for ǫ f i ∼ 0.1 − 1 and v S ∼ 100GeV − 1TeV [6].…”

“…qL [2][3][4][5][6][7]. In the basis (a) with ∆ ′ qQ = 0, the CKM unitarity violation is actually far below the experimental bounds [15].…”

“…These analyses show, in particular, that there is a good chance to find the singlet quark effects in the B physics. Some contributions of the neutral couplings mediated by the Higgs scalar particles have also been considered on the neutron electric dipole moment and the neutral meson mixings [4,6,10].…”