HERWIG7

HERWIG7
Name	HERWIG7
Developer	Herwig Collaboration
Released	2015
Programming language	C++
Operating system	Cross-platform
License	GPL

HERWIG7 HERWIG7 is a particle physics event generator used to simulate collisions and final-state interactions in high-energy physics experiments. It combines perturbative calculations with nonperturbative models to produce fully hadronized final states for use in experimental analysis, detector simulation, and theoretical studies. The project is maintained by a collaboration of particle physicists and software engineers contributing to both phenomenology and computational infrastructure.

Overview

HERWIG7 provides Monte Carlo simulation of scattering processes relevant to Large Hadron Collider, CERN, Fermilab, SLAC National Accelerator Laboratory, and similar facilities. The code interfaces with parton distribution functions developed by groups such as CTEQ, NNPDF, MSTW, MMHT, and ABM and can be used alongside tools like GEANT4, ROOT, Rivet, FastJet, and LHAPDF. The collaboration interacts with experimental programs including ATLAS, CMS, LHCb, ALICE, Tevatron experiments, and theoretical initiatives like Les Houches Accord working groups and HEPData. HERWIG7 supports a range of processes studied in contexts tied to awards and institutions such as the Nobel Prize-winning discoveries at CERN and precision measurements relevant to European Organization for Nuclear Research programs.

Features and Physics Modeling

The generator implements perturbative QCD aspects such as Next-to-Leading Order matching schemes inspired by work from groups at DESY, INFN, IPPP Durham, University of Cambridge, University of Oxford and interfaces to matrix-element providers like MadGraph, POWHEG BOX, OpenLoops, COMIX, SHERPA and MCFM. It includes parton shower algorithms that build on formalisms developed in studies at SLAC, Brookhaven National Laboratory, Los Alamos National Laboratory, Max Planck Society, and research groups connected to Harvard University, Princeton University, Massachusetts Institute of Technology, and California Institute of Technology. Hadronization models echo heritage from phenomenology associated with institutions such as Cavendish Laboratory, DESY Zeuthen, University of Manchester, and University of Glasgow. Soft QED and QCD effects, underlying event tunes, and multiple-parton interactions are tuned with data from HERA, Tevatron Run II, and LEP experiments, informed by analyses from collaborations like ALEPH, DELPHI, OPAL, and L3.

Software Architecture and Implementation

HERWIG7 is implemented primarily in C++ with object-oriented design influenced by software engineering practices common at CERN computing groups and academic teams at University of Edinburgh and University of Durham. It uses modular plugins for matrix-element interfaces, tuning configurations, and analysis hooks compatible with Rivet analysis modules. Build and continuous integration systems adopt conventions used by projects such as Boost C++ Libraries, CMake, GitLab, Jenkins, and Travis CI; code review and issue tracking reflect workflows seen in collaborations like ATLAS Experiment and CMS Collaboration. The codebase supports parallel execution models suitable for high-throughput computing centers such as NERSC, Fermilab Grid, CERN OpenLab, and regional facilities managed by GridPP.

Installation and Usage

Installation follows patterns used by scientific software stacks at CERN IT, Fermilab Scientific Computing Division, KIT, and university clusters at University of Tokyo and University of Melbourne. Users configure HERWIG7 with external libraries including LHAPDF, FastJet, and HepMC and can run steering scripts influenced by command-line interfaces from tools like MadGraph5_aMC@NLO and Sherpa. Job submission integrates with batch systems such as HTCondor, SLURM, and PBS Professional used at facilities like DESY, TRIUMF, KEK, and Brookhaven National Laboratory. Documentation and tutorials draw on examples developed in summer schools and workshops at Les Houches Summer School, CERN Summer Student Programme, and regional schools at JINR.

Validation and Performance

HERWIG7 validation relies on comparisons to data from ATLAS, CMS, LHCb, ALICE, CDF, and D0 with analyses automated through Rivet and datasets curated in HEPData. Performance benchmarks consider throughput on clusters at CERN, Fermilab, RAL, and supercomputers such as those at Oak Ridge National Laboratory and Argonne National Laboratory. Tuning campaigns have involved collaborations with experimental groups and theory teams at MPI, SISSA, IPPP Durham, and national labs, producing tunes analogous to historical efforts like the Professor tuning framework. Validation includes comparisons to precision results from NNLO calculations and resummation studies linked to research at KITP, Perimeter Institute, Institute for Advanced Study, and CPT Marseille.

Development History and Versioning

HERWIG7 evolved from earlier generations of event generators originating in work at CERN, Rutherford Appleton Laboratory, University of Manchester, and Durham University with milestones coordinated at workshops such as Les Houches Workshops and MCnet Schools. Versioning follows semantic practices common to scientific software and release processes coordinated with experiment software groups at ATLAS Collaboration and CMS Collaboration. Development has included contributions from institutions including Oxford University, Imperial College London, University of Sussex, University of California Berkeley, University of Wisconsin–Madison, and international partners in Japan, Germany, Italy, and France.

Applications and Notable Studies

HERWIG7 has been applied in collider phenomenology studies for Higgs physics relevant to the ATLAS Experiment and CMS Collaboration, top-quark analyses involving Tevatron legacy results, and beyond-Standard-Model searches connected to work at CERN. It has supported publications by collaborations at LHCb and ALICE and theoretical investigations from groups at Princeton University, Caltech, Institute for Theoretical Physics, Zurich, and KIT. Studies incorporating HERWIG7 contributed to precision determinations of strong coupling studies linked to Alpha_s extractions, jet substructure analyses tied to Boosted Object techniques developed at SLAC and DESY, and Monte Carlo comparisons in review articles produced by collaborations at IPPP Durham and IHEP Beijing.

Category:Monte Carlo event generators