Physical Review C
We study SU(3) flavor-breaking corrections to the relation between the octet baryon masses and the nucleonmeson CP-violating interactions induced by the QCD (theta) over bar term. We work within the framework of SU(3) chiral perturbation theory andwork through next-to-next-to-leading order in the SU(3) chiral expansion, which isO(m(q)(2)). At lowest order, the CP-odd couplings induced by the QCD (theta) over bar term are determined bymass splittings of the baryon octet, the classic result of Crewther et al. [Phys. Lett. B 88, 123 (1979)]. We show that for each isospin-invariant CP-violating nucleon-meson interaction there exists one relation that is respected by loop corrections up to the order we work, while other leading-order relations are violated. With these relations we extract a precise value of the pion-nucleon coupling (g) over bar (0) by using recent lattice QCD evaluations of the proton-neutron mass splitting. In addition, we derive semiprecise values for CP-violating coupling constants between heaviermesons and nucleons with similar to 30% uncertainty and discuss their phenomenological impact on electric dipole moments of nucleons and nuclei.
de Vries, J., Mereghetti, E., & Walker-Loud, A. (2015). Baryon mass splittings and strong CP violation in SU (3) chiral perturbation theory. Physical Review C, 92(4), 045201.