PAT - Physics Analysis Toolkit

Purpose

The Physics Analysis Toolkit (PAT) is a high-level analysis layer enabling the development of common analysis efforts across and within Physics analysis groups. It aims at fulfilling the needs of most CMS analyses, providing both ease-of-use for the beginner and flexibility for the advanced user.

The PAT runs in the CMS software framework (CMSSW and FWLite) and it makes use of the algorithms provided by both Offline and Physics object groups.

This documentation contains:

• A few recipes for a quick start (but reading further is recommended).
• A brief description of the overall structure of the PAT.
• More details about the actual content of the PAT.
• Contact names from PAT, PAG and POGs.
• Links to various example analyses.

Other sources of documentation:

• The CMSSW reference manual for more details (look for the pat:: namespace)
• The offline workbook tutorial on the PAT

How to start

Below a number of recipes and examples for users are provided (to be read after the full documentation ).

• PAT recipes: how to install the PAT in various releases
• PAG specific PAT analyses (below)
• PAT Examples: basic example configuration files
• PAT HowTos: a digest of frequently asked questions
• WorkBookPATTupleCreationExercise, WorkBookAnalysisStarterKit: tutorials
• SWGuidePF2PAT: using Particle Flow with PAT

Design of the PAT

Overview

The PAT workflow is divided in a series of layers as shown on the figure below:

• Layer 0 performs the "cleaning" tasks on the standard reconstructed object (in AOD or RECO formats), computes related information (e.g., Monte Carlo and trigger matching), and takes care of the low-level handling of references.
• Layer 1 collapses the output of layer 0 into compact objects containing all the necessary information.
• Layer 2 performs event-hypothesis dependent tasks: this is where the analysis starts.

The PAT workflow

The PAT consists of framework plugin modules: cleaners for layer 0, producers for layer 1. These plugins themselves call standalone algorithms and helper classes.

Notes:

• all classes are defined in the namespace pat::;
• the configuration files can be found in CMS.PhysicsTools/PatAlgos/python, ordered by task.

Tasks performed inside the PAT

• Layer 0: cleaning and association on AOD content
  • More details about the PAT cleaning and the Monte Carlo and trigger matching
• Layer 1: production of PAT objects from information gathered at Layer 0.
  • More details about PAT data formats and PAT trigger information
• Layer 2: easy access to event hypothesis structures using Layer 1 objects.
  • More on event hypothesis

PAT configuration defaults

Details of the default PAT configuration can be found in the links below.

Many thanks to KiraGrogg from the EWK group for putting these pages together.

Reducing the event size in PAT

You want to produce smaller files? Recipes for managing the event size in PAT are given in Event Size Management in the PAT.

Contact names

N.B. Please use the Physics Tools hypernews for any questions, requests, etc.

PAT main developers

POG contacts

PAG Examples and contact persons

Developer Area

Below links to document oriented to PAT developers

• PAT Developer TWiki page
• SWGuidePATv2Cleaning
• SWGuidePATv2ConversionGuide

Review status