Slides for EB3

1. Slides for EB3

2. Left Problems from EB2 • 1. Why muon triggers are not used in e channel? • 2. Add backgrounds estimation for signal search region • 3. Add expected limits for signal search: stau neutrino & Z’ • 4. In the emu channel the main bkg is ttbar. Would applying a bjet veto help? • 5. Validate Wjet background at high mass region(shape from MC) • 6. QCD bkg comes from OS/SS method, relying on results from h->tautau for validation of the technique (NOS_QCD=NSS_QCD). An independent validation might be useful • 7. some adjustments of text or format

3. Status • Update muon selection, use only high pT recommendation • We have formed a new version of supporting note including all the issues listed in slide #2 • https://cds.cern.ch/record/1622230 • waiting for the EB3 • some further consistent check for FAR, will update the note if needed

4. Update 1. add muon trigger into e channel • For emu channel(data & MC): EF e24vhi medium1||EF e60 medium1 EF e24vhi medium1||EF e60 medium1||EF mu24i tight||EF mu36 tight For Validation region (M<200GeV) ~ 5% more events

5. Update 2. add backgrounds estimation for signal search region emu etau mutau

6. Update 2. add backgrounds estimation for signal search region

7. Update 2. add backgrounds estimation for signal search region etau emu mutau

8. Update 3. Add expected limits for signal search Bayesian method is used to set limits for search

9. Update 3. Add expected limits for signal search Search for signal in a mass window for mass M signal: [M-3, M+3] Inputs: expected background number and systematics in each mass window Signal efficiency * Luminosity and systematics for each mass point e channel as an example

10. Update 3. Add expected limits for signal search Stau neutrino Z’

11. Update 4 use b tagging to veto ttbarbkgd • Ttbar background is one of the dominant background in emu channel for both validation region and signal search region. • use btagging to veto ttbar background • use MV1 method • use 70% efficiency work point • require the bjet number in a event is 0 More than 80% ttbar events are vetoed

12. Update 4 use b tagging to veto ttbarbkgd Systematics with btagging Signal efficiencies are almost not affected by the N-bjet=0 requirement ~ 1% decreased We have no gain for high mass region(M>1000GeV)

13. Update 5 Validate W+jetbkgdat high mass region Wjetbkgd is validated in a data control region • invert the cut on the angle phi between the leptons (, )(use , for an example ) • from dphi> 2.7 to 1 <dphi< 2.7 • all other cuts are kept the same as signal selection • The signal from a resonance has almost no contribution at this region whereas backgrounds are much wider. • Statistics are not great but OK

14. Update 5 Validate W+jetbkgdat high mass region

15. Update 5 Validate W+jetbkgdat high mass region W+jetEnhanced control sample • Missing Et > 30 GeV (enhance W). • Remove opposite sign requirement • Njet < 2 (reduce t‐tbar). • Remove Pt cut (increases statistics). MC says that about 90% of events are W+jet

16. Update 5 Validate W+jetbkgdat high mass region

17. Update 6 QCD test • In QCD calculation, we assumeNOS_QCD =NSS_QCD is this correct ? • Construct a data control sample and perform a validation: same requirements as signal selection expect: • reverse muon isolation requirement • add MET<10GeV • use non-isolated EF_mu36_tight trigger We quote an additional 10% uncertainty for QCD multi-jet background