Pileup Reweight/Systematic

[zhenbinwu]

During the previous evaluation of pileup reweighting and systematic, I quoted the inelastic proton-proton cross section from CMS lumi measurement paper https://arxiv.org/abs/1802.02613
68.6 +- 1.7mb.

It seems the updated recommendation from Lumi POG is 69.2 +- 4.6% https://twiki.cern.ch/twiki/bin/view/CMS/PileupJSONFileforData#Recommended_cross_section

I don't expect a large effect on the pileup reweight, but the systematic should be doubled. While the data production is getting complete, we should recalculate the pileup weight in next production :-(