Chiral Estimates of Strong CP Violation Revisited

Abstract

The effects of the CP violating $\theta$ term in the QCD Lagrangian upon low energy hadronic phenomenology are reconsidered. Strong CP violating interactions among Goldstone bosons and octet baryons are incorporated into an effective chiral Lagrangian framework. The $\theta$ term's impact upon the decays $\eta \to \pi \pi$ and ${\pi }^0\to \gamma \gamma$ is then investigated but found to be extremely small. A refined model independent estimate of nonanalytic contributions to the neutron electric dipole moment is also determined using velocity dependent Baryon Chiral Perturbation Theory. We obtain the approximate upper bound $|\theta |<4.5\times 10^{-10}$.

arXiv comment11 pages with 3 figures not included but available upon request, CALT-68-1842

Cited by in corpus (10)

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• Electric Dipole Moments of Light Nuclei From Chiral Effective Field Theory
• The Effective Chiral Lagrangian From the Theta Term
• The Nucleon Electric Dipole Form Factor From Dimension-Six Time-Reversal Violation
• The Electric Dipole Form Factor of the Nucleon in Chiral Perturbation Theory to Sub-leading Order
• The Time-Reversal- and Parity-Violating Nuclear Potential in Chiral Effective Theory
• The electric dipole form factor of the nucleon
• Parity- and time-reversal-violating nuclear forces
• Contribution of the QCD $\Theta$-term to nucleon electric dipole moment