Production and decay of radion in Randall-Sundrum model at a photon collider
A warped extra dimension model predicts an extra scalar particle beyond the Standard Model which is called a radion. Although interactions of the radion are similar to those of the Higgs boson in the Standard Model, a relatively light radion ($\lesssim 100 {\rm GeV}$) is not severely constrained from the Higgs search experiments at the LHC. In this paper we study discovery potential of the radion at a photon collider as an option of ILC. Owing to the trace anomaly of the energy-momentum tensor, both a production of radion in $γγ$ collision and its decay to gluon pair are enhanced sizably. We find that the photon collider has a sensitivity for discovering the radion in low-mass region up to $Λ_ϕ\sim 3 {\rm TeV}$, where $Λ_ϕ$ is a scale parameter which suppresses the interactions of radion to the Standard Model particles.