FeynRules

FeynRules
Name	FeynRules
Developer	California Institute of Technology, University of Geneva, Institut de Physique Théorique, CERN contributors
Released	2007
Latest release	2.x
Programming language	Mathematica
Operating system	Cross-platform
License	GPL-compatible

FeynRules FeynRules is a Mathematica-based software package for deriving Feynman rules from quantum field theory Lagrangians. It provides automated generation of interaction vertices and model files used by matrix-element generators and Monte Carlo event generators. The project was developed in collaboration with groups at California Institute of Technology, CERN, University of Geneva, Institut de Physique Théorique (IPhT), and has been used in studies connected to experiments at Large Hadron Collider, ATLAS, CMS, LHCb, and theoretical work tied to SLAC National Accelerator Laboratory, Fermilab, and DESY.

Introduction

FeynRules was motivated by needs of phenomenologists working on extensions of the Standard Model (SM), such as supersymmetric constructions motivated by Martin, Stephen and by beyond the Standard Model proposals explored at LEP, Tevatron, LHC Run 1, and LHC Run 2. The code bridges analytic model building performed at institutions like Princeton University, Harvard University, Massachusetts Institute of Technology, University of Cambridge, University of Oxford, and University of California, Berkeley with numerical tools such as MadGraph, CalcHEP, Sherpa, and PYTHIA. It has been cited in phenomenology connected to theoretical frameworks proposed by researchers from Stanford University, Columbia University, IHEP (Beijing), and Niels Bohr Institute.

Features and Capabilities

FeynRules translates Lagrangians into Feynman rules, producing vertices for propagators and interactions used in amplitude computations at collaborations including ATLAS Collaboration, CMS Collaboration, ALICE, and LHCb Collaboration. It supports implementations of gauge theories like Quantum Chromodynamics (QCD), Electroweak theory, and model classes such as Minimal Supersymmetric Standard Model (MSSM), Two-Higgs-Doublet Model (2HDM), Composite Higgs models, and effective field theories inspired by work at Institute for Advanced Study and Perimeter Institute. The package integrates symbolic manipulation features from Mathematica and has been used alongside amplitude tools such as FeynCalc, Package-X, FormCalc, and LoopTools for perturbative calculations tied to precision results from LEP Electroweak Working Group, Tevatron Electroweak Working Group, and global fits by groups at IHEP, IPPP Durham, and CERN Theory.

Installation and Usage

The distribution of FeynRules is provided as a Mathematica package with documentation used by researchers at CERN Summer Student Programme, Les Houches Workshops, SUSY Working Group, and schools at ICTP. Users load the package in Mathematica sessions on systems administered at facilities including NERSC, CERN IT, SLAC and run model files prepared by groups at University of Padua, LAPTh, LAPTh Annecy-le-Vieux, LPTHE Paris. Typical workflows export model outputs for generators run on clusters like those at GridPP, Open Science Grid, and computing centers collaborating with ATLAS Grid, CMS Tier-1 sites.

Model Implementation and Syntax

Model definitions in FeynRules encode particle content, parameters, and Lagrangian terms following conventions used in literature by authors from Johns Hopkins University, Brown University, University of Melbourne, Kyoto University, and Nagoya University. Syntax leverages Mathematica constructs and interfaces documented in tutorials presented at Les Houches Summer School, Modave Summer School, and workshops organized by HEPTools consortia. Users implement gauge groups such as SU(3), SU(2), and U(1), representations discussed in texts by Georgi, Howard and Peskin, Michael E.; they define indices and mixings for flavor structures studied in analyses by CKM and PMNS community efforts at Neutrino 202x meetings.

Interfaces and Export Formats

FeynRules produces model files compatible with matrix-element and event generators including MadGraph5_aMC@NLO, CalcHEP, CompHEP, Sherpa, WHIZARD, and parton-shower tools like PYTHIA 8 and Herwig. Output formats follow standards developed in collaborations such as the Les Houches Accord (LHA), Universal FeynRules Output (UFO), and exchange formats used by HEPData and analysis frameworks at Rivet and ROOT. Integration with one-loop tools leverages interfaces to MCFM, GoSam, OpenLoops, and uses model descriptions suitable for automation efforts at NNPDF and precision calculations tied to groups at KIT, Max Planck Institute for Physics, and Institut de Physique Nucléaire (IPN).

Validation and Benchmarking

Validation of model implementations is performed by cross-checking amplitudes and cross sections against analytical results from literature by Peskin & Schroeder, numerical comparisons with MadGraph, CalcHEP, and independent computations performed at CERN Theory Group, IPPP Durham, and university groups such as Università di Roma, Universidad de Valencia, Université de Genève. Benchmark studies often reference measurements from ATLAS, CMS, Tevatron CDF, D0 and precision electroweak results compiled by Particle Data Group. Reproducibility practices align with community standards promoted by HEPData and workflows used in collaborations like Les Houches workshops.

Development and Community

The FeynRules project has been developed by contributors affiliated with Caltech, CERN, University of Geneva, LAPTh, IPHT, and has an active user base drawn from universities and laboratories including Princeton, Stanford, Oxford, Cambridge, DESY, FERMILAB, SLAC, IHEP, and institutes participating in events such as Les Houches Workshops, Modave Summer School, SUSY Les Houches Accord meetings. Development is coordinated through collaborative platforms and discussed at conferences like ICHEP, EPS-HEP, Moriond, and in working groups related to event generator validation at HEPTools gatherings.

Category:High energy physics software