The instanton-generated $\mathrm{CP}$-violating perturbation is shown to have a form $\frac{3\overline{\theta }{m}_u{m}_d{m}_s}{(m_u{m}_d+m_u{m}_s+m_d{m}_s)}\left(\overline{\psi }i{\gamma }_5\psi \right)$ for $\overline{\theta }\ll 1$. The induced neutron electric dipole moment, evaluated in the framework of the MIT bag model, is $d_n=8.2\mathrm{}\times {10}^{-16\mathrm{}}\overline{\theta }e$ cm.

• Received 5 July 1978

DOI:https://doi.org/10.1103/PhysRevD.19.2227