Difference: RestrippingMDST (5 vs. 6)

Revision 62018-02-22 - NiklasStefanNolte

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META TOPICPARENT name="StrippingFAQ"

LHCb Stripping FAQ - Re-Stripping of MC in MicroDST format

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Motivation

Why would you want to re-strip your MicroDST?

  • You want to change your stripping cuts for efficiency studies or because your stripping selection changed for data
  • You want to fix a bug that can only be corrected by re-processing (like the TISTOS bug)
  • You want to resample your PID and therefore need to remove all PID cuts during stripping and in the standard particles.
  • some other cool idea you came up with

Although this page looks awfully long for a simple task like re-stripping, it is quite simple to accomplish. Please read carefully. Attached to this page is a working example, where you can test everything (lb-run DaVinci/vXXrXpX gaudirun.py example.py).

 

Restrictions

In the case where your MC is persisted in the DST format, reconstruction information of the entire event is saved. This is not the case for MicroDST MC. It is unlikely, that re-stripping will result in the same data-sample that you would have got if you applied your stripping line during production. However, there is an algorithm (CopySignalMCParticles) in the MicroDST production that copies reconstruction information matched to signal MC-Particles. It is important to note that the candidates you can get out of MicroDST either passed any stripping line or are truth-matched (associated to the signal MC particles). This is different to DST, where you can in principal get every candidate.

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All calculation requiring information of more than the candidate only, like Isolation variables in RelatedInfoTools, cannot be performed during MicroDST Re-stripping and must be left out.

Not every TupleTool is tested in MicroDST re-stripping. If you encounter problems with one of them, contact the creator of the tool.

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Here is a short list of additional restrictions:
 
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The presented method is not yet well validated (February 2018). It was only tested on a few Rare-Decay StrippingLines.
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  • All calculation requiring information of more than the candidate only, like Isolation variables in RelatedInfoTools, cannot be performed during MicroDST Re-stripping and must be left out.
  • Not every TupleTool is tested in MicroDST re-stripping. If you encounter problems with one of them, contact the creator of the tool.
  • (rather a warning) The presented method is not yet well validated (February 2018). It was only tested on a few Rare-Decay StrippingLines and only with DaVinci versions newer than DaVinci/v42r6p1.
 

How To

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  -- NiklasStefanNolte - 2018-02-20
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META FILEATTACHMENT attachment="Restripping_1.pdf" attr="" comment="Until the site is finished, you can find some instructions here. Contact me (Niklas Nolte) if you encounter problems with this" date="1519201918" name="Restripping_1.pdf" path="Restripping_1.pdf" size="1018035" user="nnolte" version="1"
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META FILEATTACHMENT attachment="restrip_MDST_Phi2MuMu.py.txt" attr="" comment="This is a working example of an Optsfile that restrips a MicroDST MC to nTuple (as long as the input file exists, its sim09a :D)" date="1519318527" name="restrip_MDST_Phi2MuMu.py.txt" path="restrip_MDST_Phi2MuMu.py.txt" size="7779" user="nnolte" version="1"
 
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