Higgs-Boson Mass Limit within the Randall-Sundrum Model

TL;DR

This paper analyzes how KK graviton exchanges in the Randall-Sundrum model affect unitarity in WW scattering, showing potential to relax Higgs mass limits and connect collider observations to fundamental parameters.

Contribution

It demonstrates that KK graviton exchanges can significantly extend the unitarity bounds on the Higgs mass within the Randall-Sundrum model, linking collider data to model parameters.

Findings

Unitarity is violated below the naive dimensional analysis scale when summing KK gravitons.

KK graviton exchange can allow a Higgs mass up to 1.4 TeV while maintaining unitarity.

Observation of KK gravitons at the LHC can determine model parameters and unitarity bounds.

Abstract

Perturbative unitarity for $\wlwl$ scattering is discussed within the Randall-Sundrum model. It is shown that the exchange of massive 4D Kaluza-Klein gravitons leads to amplitudes growing linearly with the CM energy squared. Summing over KK gravitons up to a scale $\lbar$ and testing unitarity at $\rts=\lbar$, one finds that unitarity is violated for $\lbar$ below the 'naive dimensional analysis' scale, $\lnda$. It is also shown that the exchange of gravitons can substantially relax the upper limit from unitarity on the mass of the Standard Model Higgs boson - consistency with unitarity for all $\rts$ below $\lbar$ is possible for $\mh$ as large as $ 1.4\tev$, depending on the curvature of the background metric. Observation of the mass and width (or cross section) of one or more KK gravitons at the LHC will directly determine the curvature and the scale $\lw$ specifying the couplings of matter to the KK gravitons. With this information and a measurement of the Higgs boson mass it will be possible to determine the precise $\rts$ value below which unitarity will remain valid.