Neutron and electron electric dipole moment inN=1supergravity unification

Abstract

An analysis of the neutron EDM and of the electron EDM in minimal Nϭ1 supergravity unification with two CP-violating phases is given. For the neutron the analysis includes the complete one loop gluino, chargino, and neutralino exchange diagrams for the electric dipole and the chromoelectric dipole operators, and also the contribution of the purely gluonic dimension-six operator. It is shown that there exist significant regions in the six-dimensional parameter space of the model where cancellations between the gluino and the chargino exchanges reduce the electric and the chromoelectric contributions, and further cancellations among the electric, the chromoelectric, and the purely gluonic parts lead to a dramatic lowering of the neutron EDM sometimes below the electron EDM value. This phenomenon gives a new mechanism, i.e., that of internal cancellations, for the suppression of the neutron EDM in supersymmetric theories. The cancellation mechanism can significantly reduce the severe fine-tuning problem associated with CP-violating phases in SUSY and SUGRA unified models. ͓S0556-2821͑98͒01203-X͔

The soft supersymmetry-breaking Lagrangian: theory and applications

“…• Certain cancellations exist between the various one-loop diagrams which contribute to EDMs [328,329,330,331,332,333] (see also [334,335,336]). These cancellations are accidental cancellations and are not due to a fundamental low energy symmetry.…”

Publisher's Note: Relic density and elastic scattering cross sections of the neutralino in the minimal supersymmetric standard model withCP-violating phases [Phys. Rev. D70, 055011 (2004)]

“…This interference leads to suppression of the annihilation cross section, and the relic density is enhanced to fit into the WMAP-allowed region for tan β = 50. The phase θ M 1 is constrained by experimentel constraints on the EDMs of the electron, the neutron [51][52][53] and 199 Hg [54]. In the present work, we do not perform a complete analysis of the EDM constraints, but only present results for the electron EDM.…”

CPViolation in Unpolarizede+e−→Charginos at One-Loop Level

“…Therefore, for equal-mass fermions in the final state (i = j) the unpolarized cross section is always P-, C-and CP-even 5 . In contrast, if the chargino species are different, CP-violating terms can arise even in the unpolarized cross-section.…”

“…It has long been known that these phases, if O(1), could lead to values for the electron and neutron electric dipole moments that would violate the experimental bounds unless the superparticles had masses of O(TeV) or higher [3]. However, it has recently been realized that there could well be cancellations among various contributions to such CP-violating effects [4,5], such that the experimental constraints are respected, even with some phases of O(1) and some superparticles light.…”