Big Signals of Little Randall-Sundrum Models

TL;DR

This paper analyzes the potential for discovering Kaluza-Klein modes, especially Z' and KK gluons, at the LHC within Little Randall-Sundrum models with a low 5D cutoff scale, highlighting early detection prospects and differences from Planck-scale models.

Contribution

It provides detailed predictions for LHC signals of KK modes in Little RS models with low M_5, including discovery thresholds and comparisons to Planck-scale models.

Findings

A 2-3 TeV Little Z' can be discovered with less than 4 fb^{-1} at 14 TeV.

Second KK mode Z'' at 4.3 TeV requires about 100 fb^{-1} at 14 TeV.

Discovery prospects for Little KK gluons are promising but challenging due to decay reconstruction.

Abstract

We examine signals at the Large Hadron Collider (LHC) of Kaluza-Klein modes, in volume-truncated "Little Randall-Sundrum" (LRS) models of flavor, characterized by 5D cutoff scales M_5 that are small compared to the 4D Planck mass M_P ~ 10^{19} GeV. In particular, for the phenomenologically viable choice M_5 ~ 10^4 TeV, the discovery of a 2 (3)-TeV "Little" Z' at the LHC requires about 1 (4) 1/fb at \sqrt{s}=10 (14) TeV, in the clean di-lepton channel. Our results highlight the possibility of probing interesting values of M_5, starting with the early LHC data. With M_5 ~ 10^4 TeV, discovering the second KK mode Z'', at about 4.3 TeV, requires O(100) 1/fb at \sqrt{s}=14 TeV, providing a probe of the warped nature of the bulk that is encoded in the mass ratio of the first two KK modes, at design luminosity. By comparison, discovering a 3-TeV Z' of the Planck-weak hierarchy models (with M_5 ~ M_P), in any channel, would require upwards of O(300) 1/fb at \sqrt{s}=14 TeV. We also point out that discovery prospects markedly improve for Little KK gluons as well, but the challenging reconstruction of their t tbar decay products may not allow an appreciable advantage for early discovery, over the Little Z' case.