  The appearance of the radion field, which is associated with the spin-0
metric fluctuations combined in some manner with the scalar stabilizing field,
and of the radion, the corresponding lowest Kaluza-Klein (KK) mode, is a
generic prediction of stabilized brane world models. In such models the radion
plays the role of the dilaton, and its mass may be somewhat smaller than that
of all the KK modes of other particles propagating in the multidimensional
bulk. Due to its origin, the radion couples to the trace of the energy-momentum
tensor of the Standard Model, the interaction Lagrangian of the radion and the
Standard Model fermions being similar to that of the SM Higgs-fermion
interactions except for additional terms, which come into play only in the case
of off-shell fermions. In the present paper it is shown that all the
contributions to perturbative amplitudes of physical processes due to these
additional terms are canceled out for both massless and massive off-shell
fermions. Thus the additional fermion-radion terms in the interaction
Lagrangian do not alter any production and decay properties of the radion
compared to those of the Higgs boson.
