Welcome to the JpsiX analysis Twiki page


This Twiki site contains instructions to perform a B -> JpsiX analysis. B-> JpsiX compromises the following channels:
  • $B_u \rightarrow J/\Psi K^+$
  • $B_d \rightarrow J/\Psi K_S$
  • $B_d \rightarrow J/\Psi K^*$
  • $B_s \rightarrow J/\Psi \Phi$
The examples on this Twiki page are supposed to take the user through the entire JpsiX analysis chain. For the analysis we use microDST's (mDST's). In the analysis chain we can identify three steps:
  • Data collection and mdst writing
  • Reading mdst's: writing NTuples/RooDataSets
  • Fitting and plotting
The scripts needed for these analysis chains are in the Erasmus P2VVProduction package. To setup the environment do the following:
SetupProject Erasmus v2r2 --build-env
getpack Phys/P2VVProduction head
The scripts are located in the directory
Located in this directory is a
file that largely explains what is written below as well.

Data collection

At this moment there is no central production of mdst's for JpsiX channels yet. Work is going on in this field, but for the moment we will have to use private sets of mdst's. Later the mdst's should be available in the bookkeeping per JpsiX channel. To see an example of the mdst writer that we plan to use to create mdst's for the working group centrally, look at
NOTE: The user in principle shouldn't touch this script and make mdst's privately.

Writing NTuples/RooDataSets

Scripts for making the RDS for the JpsiX channels are located in
Run them as follows:
SetupProject DaVinci
python -i PhysFit/P2VVProduction/JpsiXChain/mdstreaders/mdstreader*.py
  • In these scripts, lists with mdst's are called. Replace these with your own favorite mdst's you want to run over.

  • NOTE: At this moment the scripts for writing the NTuples/RooDataSets only produce RooDataSets (RDS). Later we will add the possibility to write NTuples, although the conversion from one to another shouldn't be too much work in the end anyway.
  • NOTE: Currently, the scripts to write the NTuples/RDS are in pure GaudiPython. We plan to 'translate' these scripts in Bender algorithms, which should be much easier to read and to change if one wants to make different cuts.
  • NOTE: Currently the paths to location on the TES in these scripts do not correspond to the mdst's that are being made by the mdst writer script. This will (and must) be changed very soon!

Fitting and plotting

Scripts for fitting and plotting can be found in
These scripts read the rootfiles that are produced by the mdstreader scripts. Examples of these rootfiles can be found in
In the fits, the channel can be chosen in the file ichep.cc. The fit can be performed by doing
root -l fitters/ichep.cc


Final plots can be found in
The summaries for the different selections are dubbed
The selection cuts are written down in
But these will also be summarized below.

The selections per channel:

$B_u \rightarrow J/\Psi K^+$

$B_d \rightarrow J/\Psi K_S$

$B_d \rightarrow J/\Psi K^*$

$B_s \rightarrow J/\Psi \Phi$

-- DaanVanEijk - 30-Aug-2010

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Topic revision: r4 - 2020-08-21 - TWikiAdminUser
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