Standard Model Prediction for Paramagnetic Electric Dipole Moments

Area of Science:

• Particle Physics
• Quantum Chromodynamics
• Electroweak Interactions

Background:

• Standard Model CP violation, linked to the Cabibbo-Kobayashi-Maskawa matrix, yields small predictions for electric dipole moments (EDMs).
• Existing predictions for neutron and atomic EDMs have significant uncertainties.

Purpose of the Study:

• To investigate CP-violating observables related to electron spin (paramagnetic EDMs).
• To determine if these observables can be calculated with reduced uncertainty.

Main Methods:

• Analysis of electroweak penguin diagrams and Delta I = 1/2 weak transitions in the baryon sector.
• Application of chiral perturbation theory for calculations.

Main Results:

• Paramagnetic EDMs are dominated by specific electroweak and weak transition contributions.
• The predicted size of the semileptonic operator C_S is 7x10^-16.
• This corresponds to an equivalent electron EDM d_e^eq of 1.0x10^-35 e cm.

Conclusions:

• The calculated paramagnetic EDM is 3 orders of magnitude larger than previously estimated.
• This provides a calculable observable for probing CP violation beyond current Standard Model predictions.