On LHC searches for CP-violating, dimension-6 electroweak gauge boson operators

We reconsider the prospects for observing a dimension-6, CP-violating operator involving $W^+W^-Z$ at the LHC. Firstly, we correct a number of earlier calculations of the loop contribution to the neutron electric dipole moment of a companion operator, involving $W^+W^-\gamma$, showing that measurements imply a very strong bound on the companion operator. Secondly, we quantify the link between the two operators, showing that strongly-coupled new physics could only be observable in proposed searches if it appeared at a scale below $\sim 170$ GeV. This is most unlikely, given the null results of other searches at the LHC and elsewhere.