# Gapped Continuum Kaluza-Klein spectrum

## TL;DR

This paper introduces a warped five-dimensional model with a continuum of Kaluza-Klein modes and mass gaps, which can influence Standard Model processes and potentially be observed at the LHC.

## Contribution

It presents a novel five-dimensional model with gapped KK continua, incorporating a singular metric and IR brane to achieve electroweak symmetry breaking.

## Key findings

- Bosonic KK continua have the smallest mass gaps and are most detectable at the LHC.
- Fermionic KK continuum gaps depend on localization, affecting their experimental signatures.
- Spectral functions and Green's functions are computed, showing potential modifications to Standard Model processes.

## Abstract

We consider a warped five-dimensional model with an ultraviolet (UV) brane and, on top of the Standard Model isolated modes, continua of KK modes with different mass gaps for all particles: gauge bosons, fermions, graviton, radion and Higgs boson. The model can be considered as a modelization in five dimensions of gapped unparticles. The five dimensional metric has a singularity, at a finite (infinite) value of the proper (conformal) coordinate, which is admissible as it supports finite temperature in the form of a black hole horizon. An infrared (IR) brane, with particular jumping conditions, is introduced to trigger correct electroweak breaking. The gravitational metric is AdS$_5$ near the UV brane, to solve the hierarchy problem with a fundamental Planck scale, and linear, in conformal coordinates, near the IR, as in the linear dilaton and five-dimensional clockwork models. The branes, and singularity, distances are fixed, \`a la Goldberger-Wise, by a bulk scalar field with brane potentials explicitly breaking the conformal symmetry. The bosonic continuum of KK modes with the smallest mass gap are those of gauge bosons, and so they are the most likely produced at the LHC. Mass gaps of the continuum of KK fermions do depend on their localization in the extra dimension. We have computed the spectral functions, and arbitrary Green's functions, and shown how they can modify some Standard Model processes.