Parameterization of general Z-γ-Z’ mixing in an electroweak chiral theory

Abstract: A new general parameterization with eight mixing parameters among Z, γ and an extra neutral gauge boson Z’ is proposed and subjected to phenomenological analysis. We show that in addition to the conventional Weinberg angle θ_W, there are seven other phenomenological parameters, G’,ξ,η,θ_l,θ_r, r and l, for the most general Z-γ-Z’ mixings, in which parameter G’ arises due to the presence of an extra Stueckelberg- type mass coupling. Combined with the conventional Z-Z’ mass mixing angle θ’, the remaining six parameters, ξ,η,θ_l-θ’,θ_r-θ’, r and l, are caused by general kinetic mixing. In all eight phenomenological parameters, θ_W, G’,ξ,η,θ_l,θ_r, r and l, we can determine the Z-Z’ mass mixing angle θ’ and the mass ratio M_Z=M_Z’ . The Z-γ-Z’ mixing that we discuss are based on the model-independent description of the extended electroweak chiral Lagrangian (EWCL) previously proposed by us. In addition, we show that there are eight corresponding independent theoretical coe cients in our EWCL, which are fully xed by our eight phenomenological mixing parameters. We further nd that the experimental measurability of these eight parameters does not rely on the extended neutral current for Z’, but depends on the Z-Z’ mass ratio.