Contributions to $$ZZV^*$$ ($$V=\gamma ,Z,Z'$$) couplings from CP violating flavor changing couplings

Abstract The one-loop contributions to the trilinear neutral gauge boson couplings $$ZZV^*$$ Z V ? ( $$V=\gamma ,Z,Z'$$ = ? , ? ), parametrized in terms of one CP -conserving $$f_5^{V}$$ f 5 and -violating $$f_4^{V}$$ 4 form factors, are calculated models with flavor changing current mediated by Z an extra $$Z'$$ . Analytical results presented Passarino-Veltman scalar functions. Constraints on vector axial $$\left| g_{{VZ}}^{tu}\right| < 0.0096$$ g VZ tu < 0.0096 g_{{VZ}}^{tc}\right| <0.011$$ tc 0.011 obtained from experimental data $$t\rightarrow q$$ t ? q decays. It is found that case $$ZZ\gamma ^*$$ vertex only non-vanishing factor $$f_5^{\gamma }$$ , which can be order $$10^{-3}$$ 10 - 3 whereas for $$ZZZ^*$$ both factors $$f_5^{Z}$$ $$f_4^{Z}$$ $$10^{-6}$$ 6 $$10^{-5}$$ respectively. Our estimates smaller than those predicted standard model, where absent up loop level. We also estimate $$ZZ{Z'}^{*}$$ arising diagonal non-diagonal within a few extension models. $$f_{5}^{Z'}$$ its real imaginary parts $$10^{-1}$$ 1 – $$10^{-2}$$ 2 $$ 10^{-2}$$ respectively, dominant light quarks leptons. In $$f_{5}^{Z^\prime $$10^{-4}$$ $$f_4^{Z'}$$ reach values as large $$10^{-7}$$ 7 $$10^{-8}$$ 8 largest $$Z'tq$$ couplings.