Comparison of 2 cm vs. 2 mm Reco to MC vertex matching cuts

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Background Information

• It has been noticed that in embedding without VFMCE the reconstructed vertex does not at all match the one used by the MC code for embedding.

• I have observed the same effect in the set of embedding I have done for 19.6 GeV Au+Au strangeness studies

• Since VFMCE is not available for the library in which my production is done, I have implemented a cut in StMcAnalysisMaker to reject with vertices that do not match.

• The purpose of this study is to determine what effect, if any, this procedure has on the final correction factors.

Two cuts were tried

• Require RC vertex match the MC within 2 mm or 2 cm in each coordinate

• This results in a spherical cut with radius ~3.46 mm or ~3.46 cm for the 2 mm and 2 cm cuts respectively

Overall Rejection Factor

• 35720 out of 485185 events (7.36%) were rejected by the 2 mm cut

• 18359 out of 456742 events (4.02%) were rejected by the 2 cm cut

 
The images in the table below are the overall Lambda correction factors for the various centralities.  The general conclusion is that no real difference exists within the available statistics.

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