SUSY analysis with early data

1
SUSY analysis with early data

• E. Jansen, A. Koutsman, F. Koetsveld W.
  Verkerke
• 05 august 2008

2
1-lepton mode SUSY

• SUSY in first 10 pb-1 (low mass SU4)
• Very little hope to see in data
• 10 TeV (mc08) simulation

3
Learning from SM group

• Read through SM group CSC notes meetings
• General impression
• Analyses discussed for 50pb-1 ? 1fb-1
• Only W-mass note for 15pb-1
• W/Zjets mostly focussed on MC comparisons
• All Wjets analyses use missing ET
• What can we learn about Wjets (background for
  1l-SUSY) from this years data?
• W-mass?
• x-secs?
• alpha-s?
• ratio W1jets/W2jets? ( WNjets/W(N1)Jets? )
• reconstruction efficiency?
• No mc08 data yet, so first set up analysis with
  CSC TVNtuples

4
First plots

• LooseCut samples
• gt1 jet pTgt20 gt1l pTgt10
• 6101-6118 WlnuNjets
• 8130-8159 ZllNJets
• Standard object definition
• isolated lepton
• pTgt15 GeV
• etalt2.5
• jet
• pTgt20 GeV
• Event selection
• 1 good muon (no trigger yet)
• random selection of 10pb-1

1. how can eff rise with jets? 2. W0jets pT
jet gt20?
5
First plots

• LooseCut samples
• gt1 jet pTgt20 gt1l pTgt10
• 6101-6118 WlnuNjets
• 8130-8159 ZllNJets
• Standard object definition
• isolated lepton
• pTgt15 GeV
• etalt2.5
• jet
• pTgt20 GeV
• Event selection
• 1 good muon(no trigger yet)
• random selection of 10pb-1

Why are muons reconstructed worse in W0jets
sample?
6
W-mass in Wjets
W-mass CSC Note

• Endpoint distribution of lepton pT (black) for a
  two body decay of W
• endpoint ½ W-mass
• When W has non-zero transverse momentum, the
  distribution gets smeared

lepton

• In W 1jet pT(W) - pT(leading jet)
• Boost the complete event into the restframe of W
  using the leading jet
• Effect of smearing should disappear/decrease ?
  endpoint
• Also applicable to WNjets

7
W-mass in Wjets

• Proof of principle using truth info (pdgId
  status)
• plot pT(W) vs pT(Njets)
• Pro no use of missing ET
• Con highly dependent on JES
• Now try on reconstructed jets

pT W
W 3jets
pT 3 TrueJets
W 2jets
W 1jet
pT W
pT W
pT 1 TrueJet
pT 2 TrueJets