21. Skims

The skim package is a collection of high-level analysis scripts that reduce the data set to a manageable size by applying a simple selection. The input to a skim are Belle II File Format files of processed data. The output are so-called (Advanced) user mDST files (udst) files. These files actually contain more information but fewer events.

Tip

Analysts are recommended to use skimmed udst files as input to their analysis. For an introductory lesson, take a look at Section 3.4.12.

Tip

If you would like to know which skims are available, please browse the Physics skims section of the documentation. If you would like to know which cuts are made by a particular skim, then consult the source code by clicking the [source] button on that skim in Physics skims, or by navigating to skim/scripts/skim/WGs/<your working group name>/ in the basf2 repository.

Changed in version release-06-00-00: The skim package was reorganised between releases 5 and 6. If you need your skim steering files to work with both release 5 and release 6, then please use the following type of try-except block:

try:
    # release 6+ imports
    from skim import BaseSkim, CombinedSkim
    from skim.WGs.ewp import BtoXll
except (ImportError, ModuleNotFoundError):
    # release 5 imports
    from skimExpertFunctions import BaseSkim, CombinedSkim
    from skim.ewp import BtoXll

• 21.1. Systematics skims
  • 21.1.1. Using SystematicsCombined skims
• 21.2. Physics skims
  • 21.2.1. B → charm skims
  • 21.2.2. B → charmless skims
  • 21.2.3. Charm physics skims
  • 21.2.4. Dark sector skims
  • 21.2.5. Full event interpretation skims
  • 21.2.6. Leptonic skims
  • 21.2.7. Low multiplicity skims
  • 21.2.8. Quarkonium skims
  • 21.2.9. Radiative and electroweak penguins skims
  • 21.2.10. Semileptonic skims
  • 21.2.11. Time-dependent CP-violation (TDCPV) analysis skims
  • 21.2.12. Tau-pair skims
• 21.3. Standard skim lists
  • 21.3.1. Charm lists
  • 21.3.2. Dilepton lists
  • 21.3.3. Light meson lists
  • 21.3.4. Charmless lists
• 21.4. Information for skim experts
  • 21.4.1. Writing a skim
  • 21.4.2. Building skim lists in a steering file
    • Skim flags
  • 21.4.3. Running a skim
    • b2skim-run: Run a skim
      • Sub-commands:
        • single
        • combined
        • module
    • b2skim-generate: Generate skim steering files
    • b2skim-generate-validation: Generate skim validation scripts
  • 21.4.4. Skim registry
  • 21.4.5. Testing skim performance
    • b2skim-stats-submit: Run skim scripts on test samples
    • b2skim-stats-print: Print tables of performance statistics
    • Running b2skim-stats tools on custom samples
  • 21.4.6. Core skim package API
  • 21.4.7. Utility functions for skim experts
    • Skim flag implementation
    • Per-cut retention checker
    • Skim samples framework
    • Miscellaneous utility functions
  • 21.4.8. b2skim-prod: Produce grid production requests
  • 21.4.9. b2skim-stats-total: Produce summary statistics for skim package
  • 21.4.10. lpns2yaml.py: Convert lists of LPNs to format expected by b2skim-prod