Large Extra Dimensions
Author
Priscila de Aquino
 Katholieke Universiteit Leuven & Universite Catholique de Louvain  CP3
 priscila@…
Description of the model & references
One popular aproach to solve the Hierarchy Problem of the Standard Model is to extend spacetime to higher dimensions. In this framework, the usual fourdimensional spacetime is contained in a fourdimensional brane embedded in a large structure with N additional dimensions, the bulk.
Here, we shall focus on the Large Extra Dimensional theory, where gravitational interactions are the only ones propagating into the bulk, which dilutes their coupling strength and make it appear weaker inside the fourdimensional branes. As a consequence, the graviton field will be seem as a sum of N fourdimensional particles with the same quantum numbers, but increasing mass. These excitation of the gravitons are the massive KaluzaKlein states.
In this implementation, we consider a theory with five dimensions, in which the fifth dimension is spatial and compact. We start from a generic effective Lagrangian of a unbroken gauge theory with general gauge, fermionic and scalar fields.
 Phys. Rev. D59 (1999) 105006: T. Han, J. D. Lykken, and R.J. Zhang, On KaluzaKlein states from large extra dimensions.
 ''Nucl. Phys. B544 (1999)'' : G. F. Giudice, R. Rattazzi, J. D. Wells, Quantum gravity and extra dimensions at highenergy colliders.
From this general model, we derived a realistic Large Extra Dimensional theory containing all Standard Model fields (full LED model). We only consider the lowest KaluzaKlein massive state of the graviton.
 Eur. Phys. J. C56 (2008) 435–447: K. Hagiwara, J. Kanzaki, Q. Li, and K. Mawatari, HELAS and MadGraph/MadEvent? with spin2 particles.
Model files & extensions
 Main FeynRules file for the full LED model: LED.fr.
 Example of a Mathematica® notebook loading the model and the parameters: LED.nb.
Validation
The Feynman rules for the generic LED model were explicitly checked with those available in the literature, such as the references cited above. We found complete agreement.
Unlike for other FeynRules implementations, we cannot use any matrixelement generator to compute crosssections or decayrates, because the interfaces linking FeynRules to MonteCarlo generators are not yet defined to work for a theory with spintwo particles. Therefore, we could extrapolate the results of the generic LED implementation to guess those of QCD and electromagnetic part of the full LED implementation. This check was performed and conclusive.
Attachments (2)

LED.fr
(20.7 KB) 
added by claudeduhr 9 years ago.
The model file for LED

LED.nb
(90.9 KB) 
added by claudeduhr 9 years ago.
Sample notebook
Download all attachments as: .zip