Version 2 (modified by claudeduhr, 10 years ago) (diff) 

Minimal Universal Extra Dimensions (MUED)
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 Universal Extra Dimensional theory, in which the usual Standard Model particles are free to propagate in the bulk. As a consequence, these particles will be seem on the effective theory as a tower of N 4dimensional particles with the same quantum numbers, but with increasing masses. This is called the KaluzaKlein tower. Momentum conservation in the 5dimensional spacetime generates a conserved KaluzaKlein number, which implies that different KaluzaKlein modes can not mix with eachother.
In this implementation, a theory with five dimensions is considered, in which the fifth dimension is spatial and compactified on a S1/Z2 orbifold of radius R. We start from the most general fivedimensional Lagrangian. FeynRules derives the fourdimensional lagrangian automatically by imposing dimensional reduction and integratig out the extracoordinate y.
The minimal Universal extra dimensional model is given in:
 Physical Review D 66 (2002) 056006: HC. Cheng, K.T. Matchev, M. Schmaltz, Bosonic Supersymmetry? Getting fooled at the LHC.
This implementation was based in another existing implementation in CalcHEP:
 mued.ps: A. Datta, K. Kong, K. T. Matchev, Minimal Universal Extra Dimensions in CalcHEP /CompHEP.
The masses of KaluzaKlein particles are computed via 1 loop:
 Physical Review D 66 (2002) 036005: H.C. Cheng, K. T. Matchev, M. Schmaltz, Radiative Corrections to KaluzaKlein Masses.
Model files & extensions
The MUED implementation:
 Main FeynRules files (as a tarball): MUED.tar.gz.
 Run mued.fr. This is the main file. All the other files are called by this main file.
 Example of a Mathematica® notebook loading the model and the parameters: MUED.nb.
Instructions
The MUED is implemented in unitary gauge.
 The switch FeynmanGauge (future devlopments) must thus be set to False,
 To run it in !CalcHEP the switch FeynmanGauge must be set to True when asking the !CalcHEP output, and then to False before any run.
 In MadGraph, the maximal number of particles must be increased to run the model:
 Increase the value of max_particles in params.inc in the MadGraphII directory from =2*71= to =2*81=
 Remove all excecutables in the MadGraphII directory ( =rm rf *.o=).
 recompile MadGraph by typing make in the MadGraph main directory.
Validation
In order to validate our implementation, we have checked 118 processes using a centerofmass energy of 1400 GeV. It was done the following way:
 Comparison of the builtin Madgraph StandardModel and FeynRules generated Madgraph MUED for Standard Model processes. This comparison was done using squared matrix element at given phasespace points.
 Comparison of the existing CalcHEP MUED (CHST) with the FeynRules generated ones in CalcHEP *,* Madgraph and Sherpa: CHFR, MGFR and SHFR, through the calculation of several 2 → 2 crosssections. All the checks performed were conclusive.
 Validation Table  SM + Fermions (Cross sections given in pb):
 <img width="824" alt="ValidationMUED.jpg" src="%ATTACHURLPATH%/ValidationMUED.jpg" height="2209" />
 Validation Table  Gauge (Cross sections given in pb):
 <img width="814" alt="ValidationGauge?.jpg" src="%ATTACHURLPATH%/ValidationGauge?.jpg" height="315" />
 Main.PriscilaAquino?  15 Jun 2009
Attachments (5)

ValidationMUED.jpg
(521.1 KB) 
added by PriscilaAquino 10 years ago.
Validation table MUED

ValidationGauge.jpg
(74.0 KB) 
added by PriscilaAquino 10 years ago.
Validation table gauge bosons  MUED

MUED.tar.gz
(18.6 KB) 
added by claudeduhr 9 years ago.
The model file for UED

MUED.nb
(43.8 KB) 
added by claudeduhr 9 years ago.
Sample notebook

MUED_UFO.zip
(18.3 KB) 
added by PriscilaAquino 8 years ago.
MUED model file to be used in MadGraph5.
Download all attachments as: .zip