Leptogenesis and low-energy phases

In supersymmetric models, the CP asymmetry produced in the decay of the lightest right-handed neutrino, ≡ ǫ, can be written as a function of weak scale parameters. We introduce a way of separating ǫ into contributions from the various weak-scale phases, and study the contribution of potentially measurable neutrino phases to leptogenesis. We find that the Majorana phase φ′, which could have observable effects on neutrinoless double beta decay, is important for ǫ unless there are cancellations among phases. If the phase δ can be measured at a neutrino factory, then it contributes significantly to ǫ over much of parameter space.