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Physics Analysis Toolkit (PAT)


The Physics Analysis Toolkit (PAT) is a high-level analysis layer providing the Physics Analysis Groups (PAGs) with easy access to the algorithms developed by Physics Objects Groups (POGs) in the framework of the CMSSW offline software. It aims at fulfilling the needs of most CMS analyses, providing both ease-of-use for beginners and flexibility for advanced users. This document has the following content:

  • Tutorials: A set of links to tutorials for getting started.
  • Recipes: A set of links to installation recipes and release notes for different versions of CMSSW.
  • Description: A set of links to the central description of PAT.
  • Validation: A link to the internal validation frame of PAT.
  • Support: A set of links to PAT contact people from several PAGs and POGs.

While you are preparing your analysis for a common CMS approval please follow the CMS publication guidelines linked below:

Getting Started

Tutorials & Exercises

You can find a common tutorial web page in chapter 4.2.4 Tutorial in the WorkBookPAT documentation. The most important links there are given below:

ALERT! Note: You can find a list of links to recent PAT Tutorial Sessions organised at cern at the CMS Tutorials. You can find the agendas to the last PAT Tutorial sessions listed below:

The possibility to register for upcoming tutorials will be announced via the Physics Announcements HN and Analysis Tools HN well in advance.

Installation Recipes

PAT is fully integrated into CMSSW and an Integral Part of each CMSSW Release. Therefore in general nothing needs to be done to work with PAT apart from installing the desired release version of CMSSW. Updates and bugfixes that may be checked out on top of the existing CMSSW releases can be found on the SWGuidePATRecipes. They also include a set of complete release notes, summarising all changes and feature adds, that have been applied from release to release.

Description and Documentation

You can find a central description of PAT in the WorkBookPAT documentation. The most important links there are given below:

You can find more detailed documentation of PAT on the following subpages:

  • SWGuidePATCrossCleaning: A description of the PAT support of object disambiguation.
  • SWGuidePATMCMatching: A description of the PAT support of Mote Carlo truth matching.
  • SWGuidePATTrigger: A description of the pat::TriggerEvent and the embedding of trigger matches.
  • SWGuidePATTools: A description of the tools to configure the PAT Workflow and event content.
  • SWGuidePATEventSize: A description of how to estimate the event content of a user-defined pat::Tuple.
  • SWGuidePATResolutions: A description of the PAT support of storing kinematic object resolutions.
  • SWGuidePATUserData: A description how to add user defined data to pat::Candidate.
  • SWGuidePATSelectors: A description how to use a predefined set of selector utilities within PAT.
  • SWGuidePF2PAT: A complete description of the interface of particle flow to PAT.
  • SWGuidePATRecipes: Common PAT installation recipes and release notes for different versions of CMSSW.
  • SWGuidePATFAQs: A list of frequently asked questions and answers.


Since the CMSSW_3_1_X the pat developers team has set up an integral validation system, guaranteeing the full equivalence of pat::Candidate information to all re-keyed RECO information. To learn more about PAT validation and to have a list of all releases that have been validated since follow the links listed below:


In this section you can find the links to a all kind of support, which you might want to make use of. The Starting Point For Any Question or request might be the Analysis Tools HN. In the first place more people than you might have the same question and may profit from the public answer. Moreover people might have had a similar question already before and a query of the list might already be of help.

PAT core developers:

Find a list of the most important developers below:

POG contacts:

Find a list of POG contact persons below:

PAG contacts:

Find a list of PAG contact persons below:


In this section you can find links to outdated information which will be kept for legacy reasons:

Review status

Responsible: RogerWolf Review: reviewed

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