After the first attempts to understand the fundamental forces of nature using extra spatial dimensions by Nordström and later by Kaluza and Klein, models with extra dimensions have gained a lot of popularity addressing to different theoretical problems in particle physics. This effort has led the extra dimension to be one of the leading frameworks to go beyond the Standard Model (SM).
In this framework, one of the most popular phenomenological scenarios is the Randall-Sundrum (RS) model [1] with a warped extra dimension. The most distinctive novel feature of this scenario is the existence of a spin-2 Kaluza-Klein (KK) gravitons whose masses and couplings to the SM are set by the TeV scale and therefore, the KK gravitons appear in experiments as widely separated resonances.
This webpage contains CalcHEP and MadGraph models implementing the production and decay of the lightest KK graviton at the LHC following the scenario proposed in [2,3].

Authors

  • Oleg Antipin INFN di Firenze ( oleg.antipin @ fi.infn.it)
  • Tuomas Hapola IPPP, Durham University ( tuomas.hapola @ gmail.com )

News and Bugs

  • 18.12.2013: Graviton interactions to massless gauge bosons had an extra factor of two. Thanks to Alexandra Carvalho for detecting this bug. (There is a factor of 1/2 missing from the ZZ production amplitude in ref [2].)
  • 18.12.2013: The UFO model files support automatic decay width evaluation.

Model files and instructions

We consider two scenarios with:

  • Right-handed top being localized near the TeV brane.

The link to the CalcHEP model files: SMRS_CH

The link to the MadGraph 5 (UFO) model files: SMRS_UFO

The detailed description of the model parameters, couplings and vertices are included in the following pdf file: kkgrav.pdf

The Calchep implementation supports only unitary gauge so that user has to remember to force the CalcHEP to use the unitary gauge.

  • Left-handed (t,b) doublet being localized near the TeV brane.

The link to the MadGraph 5 (UFO) model files: SMRS-left_UFO

Validation

The implementation is verified to reproduce the analytical results given in [2] as well as theoretical predictions for the various angular distributions of the decay products of the KK graviton. Please see the pdf file above for more details.

References

  • [1] Phys. Rev. Lett. 83, 3370 (1999) [ arXiv:hep-ph/9905221] – L. Randal and R. Sundrum, A large mass hierarchy from a small extra dimension.
  • [2] Phys. Rev. D76, (2007) 036006 [ arXiv:hep-ph/0701186] – K. Agashe, H. Davoudiasl, G. Perez, A. Soni, Warped Gravitons at the LHC and Beyond.
  • [3] JHEP 0709, 013 (2007) [ arXiv:hep-ph/0701150] – A. L. Fitzpatrick, J. Kaplan, L. Randall, L. -T. Wang, Searching for the Kaluza-Klein Graviton in Bulk RS Models.