Contrasting Supersymmetry and Universal Extra Dimensions at Colliders

We contrast the experimental signatures of low energy supersymmetry and the model of Universal Extra Dimensions and discuss various methods for their discrimination at hadron and lepton colliders. We study the discovery reach of hadron colliders for level 2 Kaluza-Klein modes, which would indicate the presence of extra dimensions. We also investigate the possibility to differentiate the spins of the superpartners and KK modes by means of the asymmetry method of Barr. We then review the methods for discriminating between the two scenarios at a high energy linear collider such as CLIC. We consider the processes of Kaluza-Klein muon pair production in universal extra dimensions in parallel to smuon pair production in supersymmetry. We find that the angular distributions of the final state muons, the energy spectrum of the radiative return photon and the total cross-section measurement are powerful discriminators between the two models.