Searches for Power-Law Warped Extra Dimensions

Abstract: Extra dimensions with a bulk dilaton field can be power-law warped, unlike the exponential warping in the Randall-Sundrum (RS) model. We show that this mildly warped extra dimension can address the hierarchy problem with a novel Kaluza-Klein (KK) spectrum characterized by lighter feebly coupled KK modes compared to the KK modes in the RS model. We investigate the prospects of searching for signatures of such KK modes at current and future colliders, such as the LHC, CLIC, and FCC-ee using visible decays of KK gravitons. We also update the current bounds and projected limits for the RS model and the linear dilaton (LD) model. Furthermore, we explore the long-lived regime of KK gravitons at beam dump experiments, e.g., FASER2, MATHUSLA, and SHiP, as well as constraints from astrophysical and cosmological observations. We find that combining both kinds of searches will enable comprehensive coverage of the model parameter space relevant to the electroweak hierarchy problem.