Graviton Phenomenology of Linear Dilaton Geometries

TL;DR

This paper explores the phenomenology of linear dilaton geometries in five dimensions, analyzing how their unique graviton spectra could be detected at the LHC, and compares these with Randall-Sundrum models.

Contribution

It provides a detailed analysis of graviton signatures in linear dilaton models across a range of dilaton slopes, including experimental limits and discovery potential at the LHC.

Findings

Multiple KK graviton resonances can be detected at the LHC for large dilaton slopes.

The LHC signatures for small dilaton slopes resemble those of the ADD model.

Mass gaps lead to on-shell production and decay of KK modes, affecting high-mass spectra.

Abstract

Five-dimensional geometries with a linearly varying dilaton background arise as gravity duals of TeV Little String Theories (LSTs) and provide a solution of the hierarchy problem through extra dimensions. The unique Kaluza-Klein graviton spectrum has a mass gap on the order of the dilaton slope followed by a closely spaced discretum of states. We study in detail the graviton phenomenology in this scenario, allowing the dilaton slope to vary from the MeV to the TeV scale. When the dilaton slope is large enough so that individual KK resonances can be resolved at the LHC, several of them can be discovered simultaneously and allow for the linear dilaton geometry to be uniquely identified. For much smaller values of the dilaton slope, the LHC signatures become similar to the 5-d ADD scenario while relaxing the astrophysical and experimental constraints. Due to the mass gap, the KK modes are produced on-shell and decay inside the LHC detector, modifying the diphoton and dilepton spectra at large invariant mass. Finally, we perform a similar analysis for the low curvature RS geometry. We present experimental limits and calculate the ultimate reach of a 14 TeV LHC for all the above scenarios.