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Cut optimisation on SU1. Cuts on jets’ p T Feasibility of third lepton selection SM background: Z+jets (fast). Lecce-Napoli phonemeeting – 18/7/2006. Cuts on jets’ p T. Run on full simulation SU1 point (22.6 fb -1 ).
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Cut optimisation on SU1 Cuts on jets’ pT Feasibility of third lepton selection SM background: Z+jets (fast) Lecce-Napoli phonemeeting – 18/7/2006
Cuts on jets’ pT • Run on full simulation SU1 point (22.6 fb-1). • Presently 4 jets are required to be in the event, having pT > 100, 50, 50, 50 GeV. In SU1 full this cuts signal with fraction 0.45 and SUSY bckg 0.38 • Two harder scenarios have been also considered:
Feasibility of third lepton selection • Run on full simulation SU1 point (22.6 fb-1). • Present selection based on only 2 leptons: 301 signal events out of 2196 (S/B=0.159). • Asking for 3 (or more) leptons we gain other 68 signal events out of 335 (S/B=0.255*12), where 12 is the efficiency in “guessing” the correct dilepton in selection. • No evident criteria observed for this guessing (pT, mll, ETisol, R…) • Even if we got 12=1 the total S/B would be 0.171 (no appreciable increase) while our selection efficiency would increase by a relative 20% only.
Zll+jets available ATLFAST samples Files located in: /castor/cern.ch/grid/atlas/datafiles/susy/atlfast/2006_b/ZllJetsAlpgen (same amount of muons and electrons processed)
Dilepton invariant mass in Zll Dielectrons ~ 3 GeV Dimuons ~ 10 GeV
Zll bckg on SU1 signal Normalized to 23 fb-1 m(ll)
Zll bckg on SU1 signal Normalized to 23 fb-1 m(llj)