CP-violating decays of the pseudoscalars eta and eta' and their connection to the electric dipole moment of the neutron

TL;DR

This paper estimates upper bounds on CP-violating couplings of eta and eta' mesons based on neutron electric dipole moment constraints, impacting rare decay measurements at JLab and CERN.

Contribution

It provides the first estimates linking neutron EDM limits to CP-violating meson couplings and constrains eta and eta' decay channels.

Findings

Upper bounds on eta and eta' CP-violating couplings derived from neutron EDM limits.

Constraints on eta(eta')-pi-pi CP-violating decay couplings.

Relevance for upcoming rare decay experiments at JLab and LHCb.

Abstract

Using the present upper bound on the neutron electric dipole moment, we give an estimate for the upper limit of the CP-violating couplings of the eta(eta') to the nucleon. Using this result, we then derive constraints on the CP-violating eta(eta')-pi-pi couplings, which define the two-pion CP-violating decays of the eta and eta' mesons. Our results are relevant for the running and planned measurements of rare decays of the eta and eta' mesons by the GlueX Collaboration at JLab and the LHCb Collaboration at CERN.