Search

We complete our derivation of upper limits on the CP violating ηππ and η‘ππ couplings from an analysis of their two-loop contribution to the neutron electric dipole moment (nEDM). As a result we obtain numerical upper limits for the ηππ and η‘ππ branchings and couplings which are important for planned experiments at JLab. We also derive upper limits on the CP violating θ̅parameter of QCD θ̅< 2.8 × 10−10

The data for the upper limit on the electric dipole moment of the neutron (nEDM) can be explained by using different mechanisms beyond the Standard Model (SM). The nEDM can be generated by a CP-violating transition of η and η′ mesons into pion pairs. We derive the upper limits for the rates of the CP-violating decays η(η′) → 2π are by orders of magnitude more stringent than those from existing experiments so far.