  The radion scalar field might be the lightest new particle predicted by
extra-dimensional extensions of the Standard Model. It could thus lead to the
first signatures of new physics at the LHC collider. We perform a complete
study of the radion production in association with the Z gauge boson in the
custodially protected warped model with a brane-localised Higgs boson
addressing the gauge hierarchy problem. Radion-Higgs mixing effects are
present. Such a radion production receives possibly resonant contributions from
the Kaluza-Klein excitations of the Z boson as well as the extra neutral gauge
boson (Z'). All the exchange and mixing effects induced by those heavy bosons
are taken into account in the radion coupling and rate calculations. The
investigation of the considered radion production at LHC allows to be sensitive
to some parts of the parameter space but only the ILC program at high
luminosity would cover most of the theoretically allowed parameter space via
the studied reaction. Complementary tests of the same theoretical parameters
can be realised through the high accuracy measurements of the Higgs couplings
at ILC. The generic sensitivity limits on the rates discussed for the LHC and
ILC potential reach can be applied to the searches for other (light) exotic
scalar bosons.
