Abstract

We complete our derivation of upper limits on the CP violating eta pi pi and eta'pi pi couplings from an analysis of their two-loop contributions to the neutron electric dipole moment (nEDM). We use a phenomenological Lagrangian approach which is formulated in terms of hadronic degrees of freedom-nucleons and pseudoscalar mesons. The essential part of the Lagrangian contains the CP violating couplings between eta(eta') and pions. Previously, we included photons using minimal substitution in case of the proton and charged pions. Now we extend our Lagrangian by adding the nonminimal couplings, i.e., anomalous magnetic couplings of nucleons with the photon. The obtained numerical upper limits for the eta pi pi and eta'pi pi couplings vertical bar f(eta pi pi)(M-eta(2))vertical bar < 4.4 x 10(-11) and vertical bar f(eta pi pi)(M-eta'(2))vertical bar < 3.8 x 10(-11) can be useful for the related, planned experiments at the JLab Eta Factory. Using present experimental limits on the nEDM, we derive upper limits on the CP violating (theta) over bar parameter of (theta) over bar < 4.7 x 10(-10).