Strong CP Violation and large- spin-flavor symmetry
We revisit the contribution of the QCD term to the CP violating pion-nucleon couplings and the nucleon electric dipole moment in a combined large- and chiral perturbation theory framework. In particular, we approach this issue through the emergent spin-flavor symmetry of the baryon sector at large but finite . We obtain good agreement with previous analyses for the pion-nucleon couplings and show that the large- framework indicates that tree-level contributions to the electric dipole moment possibly play a dominant role. The spin-flavor symmetry also enables us to provide novel constraints on CP violating pion- couplings as well as the electric dipole moment and transition moment.