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

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 θW, there are seven other phenomenological parameters, G', ξ, η, θ1, θr, r and l, for the most general Z-γ-Z' mixings, in which parameter G' arises due to the presence of an extra Stueckelbergtype mass coupling. Combined with the conventional Z-Z' mass mixing angle 0', the remaining six parameters, ξ, η, θl-θ', θr - θ', r and l, are caused by general kinetic mixing. In all eight phenomenological parameters, θW, G', ξ, η, θ1, θr, r and l, we can determine the Z-Z' mass mixing angle θ' and the mass ratio MZ/MZ'. 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 coefficients in our EWCL, which are fully fixed by our eight phenomenological mixing parameters. We further find 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. (authors)