LHC collider phenomenology of minimal universal extra dimensions

Abstract

We discuss the collider phenomenology of the model of Minimal Universal Extra Dimensions (MUED) at the Large hadron Collider (LHC). We derive analytical results for all relevant strong pair-production processes of two level 1 Kaluza–Klein partners and use them to validate and correct the existing MUED implementation in the fortran version of the Pythia event generator. We also develop a new implementation of the model in the C++ version of Pythia. We use our implementations in conjunction with the Checkmate package to derive the LHC bounds on MUED from a large number of published experimental analyses from Run 1 at the LHC. Program summaryProgram title:Pythia6 MUED and Pythia8 MUEDProgram Files doi:http://dx.doi.org/10.17632/fkvcgdw9j6.1Licensing provisions: CC0 1.0Programming language: Fortran and C++Journal reference of previous version: Comput. Phys. Comm. 181 (2010) 122–127Does the new version supersede the previous version?: YesReasons for new version: The Minimal Universal Extra Dimension (MUED) model was implemented in the Pythia6 event generator from version 6.4.18 onwards. The new version now allows for different masses for various level 1 KK excitations, modified and corrected subroutines to handle the kinematics and squared matrix elements. A new production process has been added. Additionally the model is now made available in the Pythia8 event generator.Summary of revisions: The Minimal Universal Extra Dimension (MUED) model implementation in the Pythia6 event generator now allows for different masses for various level 1 KK excitations. These may appear both in the final states and in the propagators of t∕u channel contributions. Routines handling the kinematics and squared matrix elements are suitably modified to incorporate correct kinematics and ensure proper interferences of diagrams. For some processes, corrections in the expressions for the existing squared matrix elements have been made. A new subprocess qq̄→g1∗g1∗ has been added. A couple of production modes (which originally had some subprocesses lumped together) are now split to handle different masses of doublet and singlet KK excitations.Nature of problem: The ongoing run of the Large Hadron Collider (LHC) at CERN continues to look for new physics Beyond the Standard Model (BSM). For many years, the only complete models which were seriously investigated by the LHC collaborations, were different versions of low energy supersymmetry: mSUGRA, gauge-mediated SUSY, anomaly-mediated SUSY, etc. The MUED model provides an interesting and motivated alternative to supersymmetry, with unique and challenging collider phenomenology. In order to study the MUED model, it was implemented in the fortran version Pythia6 general purpose event generator from version 6.4.18 onwards. The MUED model is not available in the C++ version of Pythia8.Solution method: The new implementation validates and fixes the backward compatibility and some issues in the current Pythia6 version. The model has now been implemented in the Pythia8 event generator.