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

TL;DR

The paper develops a gauge-invariant effective field theory description of neutral triple gauge couplings, showing that no dimension-six operators induce nTGC and that four independent dimension-eight operators (1 CP-even, 3 CP-odd) form a minimal basis for on-shell diboson processes. Through a systematic operator analysis using equations of motion, integration by parts, and duality relations, the authors identify the surviving operators with zero, two, or four Higgs fields, and isolate a finite set that generate nTGC. Phenomenological studies of ZZ and AZ production reveal that the CP-even operator can contribute to on-shell processes, but SM–NP interference is strongly suppressed due to polarization mismatches, while the NP effects grow with energy yet remain small for plausible new-physics scales. The work provides explicit operator mappings, discusses current experimental bounds, and implements the operators in a FeynRules/MadGraph framework to enable collider studies of these nTGC signatures.

Abstract

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.