== Randall-Sundrum model ==

=== Author ===

Priscila de Aquino
   * Katholieke Universiteit Leuven & Universite Catholique de Louvain - CP3 
   * priscila@itf.fys.kuleuven.be
=== Description of the model & references ===

One popular approach to solve the Hierarchy Problem of the Standard Model is to extend space-time to higher dimensions. In this framework, the usual four-dimensional space-time is contained in a four-dimensional brane embedded in a large structure with N additional dimensions, the bulk.

Here, we shall focus on the Randall-Sundrum theory, where gravitational interactions are the only ones propagating into the bulk, which dilutes their coupling strength and make it appear weaker inside the four-dimensional branes. As a consequence, the graviton field will be seem as a sum of N four-dimensional particles with the same quantum numbers, but increasing mass. These excitation of the gravitons are the massive Kaluza-Klein states.

In this implementation, we consider a theory with five dimensions, in which the fifth dimension is spatial and compact. The higher dimensional metric is warped by a exponential factor. We start from a generic effective Lagrangian of a unbroken gauge theory with general gauge, fermionic and scalar fields.

   * [http://prola.aps.org/abstract/PRD/v59/i10/e105006 Phys. Rev. D59 (1999) 105006]: T. Han, J. D. Lykken, and R.-J. Zhang, ''On Kaluza-Klein states from large extra dimensions''. 
   * [http://xxx.lanl.gov/abs/hep-ph/9811291  ''Nucl. Phys. B544 (1999)'' ]: G. F. Giudice, R. Rattazzi, J. D. Wells, ''Quantum gravity and extra dimensions at high-energy colliders.'' \

Notice that these references are applied for the LED theory. Here, the effective coupling (graviton with the SM fields) is different and depends on the exponential factor of the 5D metric.

From this general model, we derived a realistic Large Extra Dimensional theory containing all Standard Model fields (full RS model). We only consider the lowest Kaluza-Klein massive state of the graviton.
   * [http://xxx.lanl.gov/abs/0805.2554 Eur. Phys. J. C56 (2008) 435–447]: K. Hagiwara, J. Kanzaki, Q. Li, and K. Mawatari, ''HELAS and MadGraph/MadEvent with spin-2 particles''. 

=== Model files & extensions ===
   * Main !FeynRules file for the full RS model: [http://feynrules.irmp.ucl.ac.be/attachment/wiki/RSmodel/RS.fr RS.fr] 
   * Example of a Mathematica® notebook loading the model and the parameters: [http://feynrules.irmp.ucl.ac.be/attachment/wiki/RSmodel/RS.nb RS.nb].