Here are some updates:
1. The "refmult_check.txt" is the code for pile up removal by double NBD fit.
2. The  "refmult_check_gau.txt" is the code for pile up removal by gaussian (peak) and NBD fit (tail).
3."TOFMult_refMult_noWei_qaSep11" shows the nBTOFMult-RefMult after the pileup cut for 27 GeV trigger 610051.
4. "ProjectingTofMult" eps are the projection plots for TofMult-refMult after we did the pile up removal for TofMatch-refMult. We try it within only one trigger (trigger for all these 3 plots is 610051), there are still second peak in low TofMult which we don't expect. 
5. The previous centrality meeting's slides:
https://drupal.star.bnl.gov/STAR/system/files/centrality_meeting_pileup_study_fundanBNL.pdf