Yang, MZ (reprint author), ACAD SINICA,INST HIGH ENERGY PHYS,POB 9184,BEIJING 100039,PEOPLES R CHINA.
The fourth rank polarization tensor and the helicity amplitudes of Z --> 3 gamma via charged Higgs boson loops in some nonstandard models with more than one Higgs doublet are calculated by using a nonlinear R(xi) gauge. The results are presented in terms of three transcendental functions of B(x), T(x) and I(x, y). We have checked the analytic results in Ref.  in comparison with ours.