Radion in Randall-Sundrum model at the LHC and photon collider

A warped extra dimension model proposed by Randall and Sundrum(RS) is one of the attractive candidates to solve the gauge hierarchy problem in the Standard Model. In a simplest version of the RS model, there are only two extra particles beyond the Standard Model - a spin-2 graviton (and its Kaluza-Klein excitations) and a radion which is a spin-0 and electrically neutral particle. In this paper, we discuss a possibility of discovering the radion at a photon collider, which has been considered as an option of $e^+ e^-$ liner collider (ILC), focusing on characteristic features of radion interactions with photon or gluon, in addition to constraints on mass and coupling of the radion from the SM Higgs boson search at the LHC.