Probe of the radion-Higgs mixing in the Randall-Sundrum model at e ⁺e^- colliders

In the Randall-Sundrum model, the radion-Higgs mixing is weakly suppressed by the effective electroweak scale. A novel feature of the existence of gravity-scalar mixing would be a sizable three-point vertex, h _μν⁽ⁿ⁾-h-φ. We study this vertex in the process e⁺e^- → h φ, which is allowed only with a nonzero radion-Higgs mixing. It is shown that the angular distribution is a unique characteristic of the exchange of massive spin-2 gravitons, and the total cross section at the future e⁺e^- colliders is big enough to cover a large portion of the parameter space that the LEP or LEP II data cannot constrain.