CP violation in the hyperon decays Σ → Nπ

A bstract 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 + → pπ 0 . 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 ε and ε ′ 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 Ξ → Λ π 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.