Looking For TeV-Scale Strings and Extra-Dimensions

TL;DR

This paper explores the experimental signatures of TeV-scale strings and extra dimensions in type I brane models, analyzing how Kaluza-Klein excitations and string effects could be detected at the LHC, with potential to probe scales up to 20 TeV.

Contribution

It provides a detailed analysis of how different configurations of gauge fields in extra dimensions affect observable signatures and the potential reach of the LHC in detecting these phenomena.

Findings

Resonance detection possible below 6 TeV

LHC can probe up to 20 TeV for gluon excitations

Virtual effects could be observed at higher scales

Abstract

In contrast to the old heterotic string case, the (weakly coupled) type I brane framework allows to have all, part or none of the standard model gauge group factors propagating in large extra--dimensions of TeV$^{-1}$ size. We investigate the main experimental signatures of these possibilities, related to the production of Kaluza-Klein excitations of gluons and electroweak gauge bosons. A discovery through direct observation of resonances is possible only for compactification scales below 6 TeV. However effects due to exchange of virtual Kaluza-Klein excitations could be observed for higher scales. We find that LHC can probe compactification scales as high as 20 TeV for excitations of gluons and 8-15 TeV for excitations of electroweak gauge bosons. Finally, in the case where no gauge boson feels the extra-dimension, we find that effective contact interactions due to massive string mode oscillations dominate those due to the exchange of Kaluza-Klein excitations of gravitons and could be used to obtain bounds on the string scale.