CP violation in the hyperon decays Σ Nπ

The study of CP violation in hyperon transitions has a long history. In the early 2000s the HyperCP experiment made a major effort to seek CP-odd signals in the decay sequence Ξ^-Λπ^- and Λ pπ^-, which motivated more searches. Most recently the BESIII and LHCb Collaborations have acquired or improved the upper bounds on CP violation in a variety of hyperon nonleptonic processes, including Σ^+ nπ^+ and Σ^+ pπ⁰. These measurements have not reached the standard-model level yet, but have stimulated a renewed interest in CP-violating new physics in strange-quark decay beyond what is constrained by the parameters and ^ from the kaon sector. In this paper, after updating the standard-model expectations for CP-odd observables in the modes Σ^ Nπ, we revisit new-physics scenarios that could enhance the corresponding quantities in Λ Nπ and ΞΛπ and apply them to the Σ^ modes. We find that the CP asymmetries in the latter can be significantly increased over the standard-model expectations, at levels which may be tested in the ongoing BESIII experiment and in future endeavors such as PANDA and the Super Tau Charm Facility.