The pure electroweak mechanism for the [Formula presented]-odd dipole moments of the quark is studied in the Kobayashi-Maskawa model. We demonstrate the nonvanishing of the weak electric dipole moment at the lowest possible two-loop level. The weak electric dipole moment of the [Formula presented] quark is calculated in the standard model with one additional heavy generation of fermions. It is found to reach [Formula presented] cm with the most optimistic assumptions about unknown masses and mixing angles. We consider also the electroweak three-loop mechanism for the electric and chromoelectric dipole moments of light quarks and find it to be negligible in the SM case. In the presence of the fourth heavy generation, however, pure electroweak corrections are important and might be several times larger than the corresponding QCD contribution for the masses of the heaviest quarks ∼ 500-600 GeV. The resulting electric dipole moment of the neutron naturally arises at the level of [Formula presented] cm.
|Original language||English (US)|
|Number of pages||4|
|Journal||Physical Review D - Particles, Fields, Gravitation and Cosmology|
|State||Published - 1996|
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