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:
How to start
Below a number of recipes and examples for users are provided (to be read
after the full documentation

).
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:
Tasks performed inside the PAT
- Layer 0: cleaning and association on AOD content
- Layer 1: production of PAT objects from information gathered at Layer 0.
- Layer 2: easy access to event hypothesis structures using Layer 1 objects.
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
Review status