D vs d: CP Violation in Beta Decay and Electric Dipole Moments

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The T-odd correlation coefficient D in nuclear beta decay probes CP violation in many theories beyond the Standard Model. We provide an analysis for how large D can be in light of constraints from electric dipole moment (EDM) searches. We argue that the neutron EDM dₙ currently provides the strongest constraint on D, which is 10 - 10³ times stronger than current direct limits on D (depending on the model). In particular, contributions to D in leptoquark models (previously regarded as "EDM safe") are more constrained than previously thought. Bounds on D can be weakened only by fine-tuned cancellations or if theoretical uncertainties are larger than estimated in dₙ. We also study implications for D from mercury and deuteron EDMs.