E. Braaten, C.S. Li, T.C. Yuan, "The evolution of Weinberg's gluonic CP-Violation operator," Physical Review Letters, 64:1709-12, 1990.

Eric Braaten (Northwestern University, Evanston, Ill.): "A great mystery in elementary particle physics is the existence of an extremely weak force that is not invariant under reversing the direction of time. In 1989, Steven Weinberg proposed a new mechanism for producing violations of time reversal (or CP) symmetry [Physical Review Letters, 63:2333-6]. He showed that particles too heavy to have been produced in the lab could induce a time reversal-violating interaction among gluons. This could be detected experimentally, because it would generate a tiny electric dipole moment for the neutron. We calculated precisely the low-energy gluon interaction that would be induced by the heavy particles. The interaction turned out to be several orders of magnitude weaker than previously believed. Extremely sensitive measurements of the neutron electric dipole moment are now being...

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