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 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 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 4-dimensional particles with the same quantum numbers, but with increasing masses. This is called the Kaluza-Klein tower. Momentum conservation in the 5-dimensional space-time generates a conserved Kaluza-Klein number, which implies that different Kaluza-Klein modes can not mix with each other.
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 five-dimensional Lagrangian. FeynRules derives the four-dimensional lagrangian automatically by imposing dimensional reduction and integrating out the extra-coordinate y.
The minimal Universal extra dimensional model is given in:
- Physical Review D 66 (2002) 056006: H-C. 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 Kaluza-Klein particles are computed via 1 loop:
- Physical Review D 66 (2002) 036005: H.-C. Cheng, K. T. Matchev, M. Schmaltz, Radiative Corrections to Kaluza-Klein Masses.
Model files & extensions
The MUED implementation:
- Main FeynRules files (as a tar-ball): 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 toFalse
, - To run it in CalcHEP the switch
FeynmanGauge
must be set toTrue
when asking the !CalcHEP output, and then toFalse
before any run. - In MadGraph, the maximal number of particles must be increased to run the model:
- Increase the value of
max_particles
inparams.inc
in theMadGraphII
directory from2**7-1
to2**8-1
- Remove all excecutables in the
MadGraphII
directory (rm -rf *.o
). - recompile MadGraph by typing
make
in the MadGraph main directory.
- Increase the value of
Validation
In order to validate our implementation, we have checked 118 processes using a center-of-mass energy of 1400 GeV. It was done the following way:
- Comparison of the built-in Madgraph Standard-Model and FeynRules generated Madgraph MUED for Standard Model processes. This comparison was done using squared matrix element at given phase-space points.
- Comparison of the existing CalcHEP MUED (CH-ST) with the FeynRules generated ones in CalcHEP, Madgraph and Sherpa: CH-FR, MG-FR and SH-FR, through the calculation of several 2-to-2 cross-sections. All the checks performed were conclusive.
- Validation Table - SM + Fermions (Cross sections given in pb): ValidationMUED.jpg
- Validation Table - Gauge (Cross sections given in pb): ValidationGauge.jpg
Attachments (5)
-
ValidationMUED.jpg
(521.1 KB
) - added by 14 years ago.
Validation table MUED
-
ValidationGauge.jpg
(74.0 KB
) - added by 14 years ago.
Validation table gauge bosons - MUED
-
MUED.tar.gz
(18.6 KB
) - added by 13 years ago.
The model file for UED
-
MUED.nb
(43.8 KB
) - added by 13 years ago.
Sample notebook
-
MUED_UFO.zip
(18.3 KB
) - added by 12 years ago.
MUED model file to be used in MadGraph5.
Download all attachments as: .zip