skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: PYTHIA 6.4 Physics and Manual

Abstract

The Pythia program can be used to generate high-energy-physics ''events'', i.e. sets of outgoing particles produced in the interactions between two incoming particles. The objective is to provide as accurate as possible a representation of event properties in a wide range of reactions, within and beyond the Standard Model, with emphasis on those where strong interactions play a role, directly or indirectly, and therefore multihadronic final states are produced. The physics is then not understood well enough to give an exact description; instead the program has to be based on a combination of analytical results and various QCD-based models. This physics input is summarized here, for areas such as hard subprocesses, initial- and final-state parton showers, underlying events and beam remnants, fragmentation and decays, and much more. Furthermore, extensive information is provided on all program elements: subroutines and functions, switches and parameters, and particle and process data. This should allow the user to tailor the generation task to the topics of interest.

Authors:
; ; ; ;
Publication Date:
Research Org.:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
892515
Report Number(s):
FERMILAB-PUB-06-052-CD-T
arXiv eprint number hep-ph/0603175; TRN: US200716%%429
DOE Contract Number:
AC02-76CH03000
Resource Type:
Journal Article
Resource Relation:
Journal Name: JHEP 0605:026,2006; Journal Volume: 06; Journal Issue: 05
Country of Publication:
United States
Language:
English
Subject:
99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE, 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; FRAGMENTATION; HIGH ENERGY PHYSICS; PHYSICS; STANDARD MODEL; STRONG INTERACTIONS; SWITCHES; Computing, Phenomenology-HEP

Citation Formats

Sjostrand, Torbjorn, /Lund U., Dept. Theor. Phys., Mrenna, Stephen, Skands, Peter, and /Fermilab. PYTHIA 6.4 Physics and Manual. United States: N. p., 2006. Web. doi:10.1088/1126-6708/2006/05/026.
Sjostrand, Torbjorn, /Lund U., Dept. Theor. Phys., Mrenna, Stephen, Skands, Peter, & /Fermilab. PYTHIA 6.4 Physics and Manual. United States. doi:10.1088/1126-6708/2006/05/026.
Sjostrand, Torbjorn, /Lund U., Dept. Theor. Phys., Mrenna, Stephen, Skands, Peter, and /Fermilab. Wed . "PYTHIA 6.4 Physics and Manual". United States. doi:10.1088/1126-6708/2006/05/026. https://www.osti.gov/servlets/purl/892515.
@article{osti_892515,
title = {PYTHIA 6.4 Physics and Manual},
author = {Sjostrand, Torbjorn and /Lund U., Dept. Theor. Phys. and Mrenna, Stephen and Skands, Peter and /Fermilab},
abstractNote = {The Pythia program can be used to generate high-energy-physics ''events'', i.e. sets of outgoing particles produced in the interactions between two incoming particles. The objective is to provide as accurate as possible a representation of event properties in a wide range of reactions, within and beyond the Standard Model, with emphasis on those where strong interactions play a role, directly or indirectly, and therefore multihadronic final states are produced. The physics is then not understood well enough to give an exact description; instead the program has to be based on a combination of analytical results and various QCD-based models. This physics input is summarized here, for areas such as hard subprocesses, initial- and final-state parton showers, underlying events and beam remnants, fragmentation and decays, and much more. Furthermore, extensive information is provided on all program elements: subroutines and functions, switches and parameters, and particle and process data. This should allow the user to tailor the generation task to the topics of interest.},
doi = {10.1088/1126-6708/2006/05/026},
journal = {JHEP 0605:026,2006},
number = 05,
volume = 06,
place = {United States},
year = {Wed Mar 01 00:00:00 EST 2006},
month = {Wed Mar 01 00:00:00 EST 2006}
}
  • SPYTHIA is an event level Monte Carlo program which simulates particle production and decay at lepton and hadron colliders in the Minimal Supersymmetric Standard Model (MSSM). It is an extension of PYTHIA 5.7, with all of its previous capabilities. This paper is meant to supplement the PYTHIA/JETSET user manual, providing a description of the new particle spectrum, hard scattering processes, and decay modes. Several examples of using the program are provided.
  • The Pythia program is a standard tool for the generation of events in high-energy collisions, comprising a coherent set of physics models for the evolution from a few-body hard process to a complex multiparticle final state. It contains a library of hard processes, models for initial- and final-state parton showers, matching and merging methods between hard processes and parton showers, multiparton interactions, beam remnants, string fragmentation and particle decays. It also has a set of utilities and several interfaces to external programs. Pythia 8.2 is the second main release after the complete rewrite from Fortran to C++, and now hasmore » reached such a maturity that it offers a complete replacement for most applications, notably for LHC physics studies. Lastly, the many new features should allow an improved description of data.« less
  • Cited by 8
  • In the era of precision physics measurements at the LHC, efficient and exhaustive estimations of theoretical uncertainties play an increasingly crucial role. In the context of Monte Carlo (MC) event generators, the estimation of such uncertainties traditionally requires independent MC runs for each variation, for a linear increase in total run time. In this work, we report on an automated evaluation of the dominant (renormalization-scale and nonsingular) perturbative uncertainties in the pythia 8 event generator, with only a modest computational overhead. Each generated event is accompanied by a vector of alternative weights (one for each uncertainty variation), with each set separatelymore » preserving the total cross section. Explicit scale-compensating terms can be included, reflecting known coefficients of higher-order splitting terms and reducing the effect of the variations. In conclusion, the formalism also allows for the enhancement of rare partonic splittings, such as g→bb¯ and q→qγ, to obtain weighted samples enriched in these splittings while preserving the correct physical Sudakov factors.« less