Search for Kaluza-Klein gravitons in extra dimension models via forward detectors at the LHC

TL;DR

This paper explores how forward detectors at the LHC can be used to detect signals of Kaluza-Klein gravitons from extra dimension models, setting new constraints on model parameters based on simulated data.

Contribution

It introduces a novel method using forward detectors to constrain Kaluza-Klein graviton models at the LHC, including both ADD and RS models.

Findings

Lower bound on ADD cutoff scale: 6.3 TeV at 95% CL

RS model first excited graviton mass limits: 2.0 TeV (k/ M_Pl=0.1), 0.5 TeV (k/ M_Pl=0.01)

Constraints derived with 200 fb$^{-1}$ at 14 TeV

Abstract

We investigate contributions of Kaluza-Klein (KK) graviton in extra dimension models to the process $pp \to p\gamma p \to p\gamma j X$, where a proton emits a quasireal photon and is detected by using the very forward detectors planned at the LHC. In addition to the $\gamma q$ initial state as in the Compton scattering in the standard model, the $\gamma g$ scattering contributes through the $t$-channel exchange of KK gravitons. Taking account of pileup contributions to the background and examining viable kinematical cuts, constraints on the parameter space of both the ADD (Arkani-Hamed, Dimopoulos and Dvali) model and the RS (Randall and Sundrum) model are studied. With 200 fb$^{-1}$ data at a center-of-mass energy of 14 TeV, the expected lower bound on the cut-off scale for the ADD model is 6.3 TeV at 95% confidence level, while a lower limit of 2.0 (0.5) TeV is set on the mass of the first excited graviton with the coupling parameter $k/\overline{M}_{\rm Pl}=0.1$ (0.01) for the RS model.