Belle II Software Documentation

This document contains documentation of the Belle II software, its command line tools and the Python programming interface.

Note

Generated on Feb 03, 2026 for release development, commit 846803ce06.

In case of questions regarding the Belle II software or for additional information, please check Belle II Questions.

Tip

If you are new to the Belle II software, you might want to take a look at the Beginners’ Tutorials, a series of lessons that get you started in no time!

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• 1. What’s New
• 2. Installation and Setup
  • 2.1. Setup of the Belle II Software
  • 2.2. Belle II Software Tools
  • 2.3. Local Installation
  • 2.4. b2venv: Using basf2 in a virtual environment
  • 2.5. Upgrading Python packages in the virtual environment
• 3. Beginners’ Tutorials
  • 3.1. Welcome!
  • 3.2. Fundamentals
  • 3.3. Software Prerequisites
  • 3.4. Working with Belle II software.
  • 3.5. Offline analysis
  • 3.6. Data model and computing
  • 3.7. Workflow Management
  • 3.8. Join us
• 4. Command Line Tools
  • 4.1. basf2: The Main Belle2 Software Executable
  • 4.2. Tools for file handling
  • 4.3. Testing Tools
  • 4.4. Tools which will provide you help
  • 4.5. Tools to help with debugging and checking code quality
  • 4.6. b2conditionsdb: Conditions DB interface
  • 4.7. Tools for luminosity
  • 4.8. Tools for ParticleStats
• 5. Belle II Python Interface
  • 5.1. Modules and Paths
  • 5.2. Logging
  • 5.3. Module Statistics
  • 5.4. Conditions Database
  • 5.5. Additional Functions
  • 5.6. Pythonizations
  • 5.7. Other Modules
• 6. List of Core Modules
• 7. Analysis
  • 7.1. Particles
  • 7.2. Modular analysis convenience functions
  • 7.3. Variables
  • 7.4. Output for offline analysis
  • 7.5. Vertex (and kinematic) fitting
  • 7.6. Event based analysis
  • 7.7. Truth-matching
  • 7.8. Advanced Topics
  • 7.9. Full list of analysis modules
• 8. B2BII
  • 8.1. Overview
  • 8.2. B2BII Analysis
  • 8.3. Converted data objects and other information
  • 8.4. Belle MDST samples
  • 8.5. FAQ
  • 8.6. b2bii functions
• 9. Background Package
  • 9.1. Useful Python Tools:
  • 9.2. Modules
• 10. Calibration
  • 10.1. Calibration Framework (CAF)
  • 10.2. Prompt Calibration
• 11. Decay Files
  • 11.1. Event Type
• 12. The Belle II Event Display
  • 12.1. Starting the display
  • 12.2. Viewer navigation and the user interface
  • 12.3. Visualised objects
  • 12.4. Window management
  • 12.5. Troubleshooting
  • 12.6. Module documentation
• 13. Event Generators
  • 13.1. Generators python modules
  • 13.2. Modules in the Generators Package
  • 13.3. SmartBKG: Selective background simulation using graph neural networks
  • 13.4. Validation
• 14. Tools for Validation of the SoftwareTrigger
  • 14.1. b2hlt_combine_results.py
• 15. KLM (\(K_{L}^0\) and Muon Detector)
  • 15.1. Modules
  • 15.2. Clusterization
  • 15.3. Muon identification
  • 15.4. Calibration
  • 15.5. Tools
• 16. Belle II File Format
  • 16.1. Python interface
  • 16.2. C++ dataobjects
  • 16.3. ROOT and compatibility guarantee
  • 16.4. Related packages
• 17. MVA package
  • 17.1. Overview
  • 17.2. Supported frameworks/backends
  • 17.3. Using the mva package
  • 17.4. How to upload/download the training into the database
  • 17.5. Examples
  • 17.6. Contributions
  • 17.7. Python-based frameworks
  • 17.8. Backward Compatibility
  • 17.9. Reading List
• 18. PXD
  • 18.1. Background Generator
• 19. Reconstruction
  • 19.1. Functions in reconstructions.py
• 20. Simulation
  • 20.1. Geant4 version in the externals library
  • 20.2. Physics list for Geant4
  • 20.3. Secondary particles
  • 20.4. FullSim
  • 20.5. Functions in simulation.py
• 21. Skims
  • 21.1. Systematics skims
  • 21.2. Physics skims
  • 21.3. Standard skim lists
  • 21.4. Information for skim experts
• 22. SVD
  • 22.1. SVD Reconstruction
  • 22.2. SVD Offline Calibration
  • 22.3. SVD Simulation
  • 22.4. SVD Tools
  • 22.5. SVD Utility Functions
  • 22.6. SVD DQM
  • 22.7. SVD DataStore
  • 22.8. SVD DBStore
  • 22.9. SVD Variables
• 23. Tracking
  • 23.1. Track Parameterization
  • 23.2. Track Finding Algorithms
  • 23.3. Track Fitting
  • 23.4. Tracking for Special Classes of Tracks
  • 23.5. Track Refining
  • 23.6. Track Matching
  • 23.7. Time Extraction
  • 23.8. PXD ROI Finding
  • 23.9. Tracking Calibrations
  • 23.10. Tracking Utility Functions
  • 23.11. Tools
  • 23.12. More (?)
• 24. TRG
  • 24.1. Trigger and TSIM
  • 24.2. Functions in L1trigger.py
• 25. Tools for Physics Validation of the Software
  • 25.1. Command line utilities
  • 25.2. Convenience Functions
• 26. Fitting Resources
  • 26.1. BAT
  • 26.2. Hydra
  • 26.3. pyhf
  • 26.4. RooFit
  • 26.5. zfit
• 27. Software development
  • 27.1. How to write basf2 code (coding conventions)
  • 27.2. Updating the main globaltag
• 28. How to document your code with Sphinx
  • 28.1. Documentation of Python Code
  • 28.2. Referencing Components
  • 28.3. Inserting Figures
  • 28.4. Documentation of Variables and Modules in C++
  • 28.5. Google Style Docstrings
  • 28.6. Add basf2 Modules Documentation to Sphinx
  • 28.7. Add basf2 Variables Documentation to Sphinx
  • 28.8. Additional Features
  • 28.9. Additional boxes for the online lessons
  • 28.10. How to test locally
  • 28.11. Previewing documentation changes in a merge request
• 29. Software publications
  • 29.1. Papers
  • 29.2. Conference proceedings
  • 29.3. Additional publications

Indices and tables

• Index

• Module Index

• basf2 Module Index

• basf2 Variable Index

• Search Page