THE CONTINUUM LINEAR DILATON

Continuum spectra can be a way out to alleviate the tension generated by the elusiveness of narrow resonances of new physics in direct experimental searches. Motivated by the latter, we consider the linear dilaton model with a continuum spectrum of KK modes. It is provided by a critical exponential bulk potential for the scalar field stabilizing the distance, between the UV boundary at y = 0 and a naked (good) singularity at y = ys, in proper coordinates, which corresponds in conformal coordinates to zs → ∞. The cutoff Ms in this theory is an intermediate scale Ms ' 10−5MPl and the warped factor solves the hierarchy between Ms and the TeV, while the hierarchy between MPl and Ms has to be solved by a (Little) String Theory with coupling gs ' 10−5. The Standard Model is localized on a 4D IR brane. The graviton and radion Green’s and spectral functions have a continuum of states with a TeV mass gap, and isolated poles consisting of the 4D graviton and the light radion/dilaton. We construct the effective field theory below the mass gap where the continua of KK modes are integrated out, generating a set of dimension eight operators which contribute to low-energy electroweak precision observables, and high-energy violation of unitarity in vector boson scattering processes. The radion mass depends on the stabilizing UV brane potential and its wave function is localized toward the IR which enhances its coupling with the SM fields. © 2021 Jagellonian University. All rights reserved.