A basis of dimension-eight operators for anomalous neutral triple gauge boson interactions

Four independent dimension-eight operators give rise to anomalous neutral triple gauge boson interactions, one CP-even and three CP-odd. Only the CP-even operator interferes with the Standard Model for the production of a pair of on-shell neutral bosons. However, the effects are found to be tiny due mainly to the mismatch of the Z boson polarization between the productions from the SM and the new operator.
Comment: 13 pages, v2 : typo corrected in eqs., ref. added, published version