L2Offline MET - PowerPoint PPT Presentation

Title: L2Offline MET


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L2/Offline MET
PRS Physics Reconstruction and
Selection HCAL/JetsMET group

• Pal Hidas
• (Shuichi Kunori)
• 08-Feb-2002

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SUSY Probing Points
(S.Abdullin)
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Complex SUSY Channel- an example -
40 60
m 0 m 1/2 (1425,312)
Mh 116GeV Mgluino 804GeV Msquark
1500GeV
( a SUSY point from hep-ph/0105204)
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qqH(120), H?invisible

• Event selection
• 2 FWD tag jets
• Et gt 40GeV
• Dhgt4.4, h1h2lt0.0
• M(jj) gt 1200GeV
• Between 2 FWD jets
• no jet
• Etgt20GeV
• no lepton
• pt(m) gt 5 GeV
• pt(e) gt 10GeV
• METgt100GeV
• DF(jj) lt 1.0

• q
• Invisible
• (neutralinos)
• (gravitinos)
• q

Signal (sBR) 4300fb (BR1) Background
QCD Zjj QCD Wjj EW Zjj EW Wjj
NB tt is no more major background.
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Reconstruction and Selection

• MET Reconstruction
• Vector sum of ET in ECALHCAL towers
• Threshold ET(tower)gt0.5GeV
• Energy scale correction (not applied in this
  analysis)
• Jet energy correction for found jets and
  min-bias correction for outside of the jets
  (cone).
• Event Selection
• Filter to remove abnormal events and/or channels
• CMSIM120 large energy deposit in single readout
• Due to 1) wrong choice of a GEANT parameter for
  energy loss and 2) memory collapse(?) in CMSIM
• ET(1x1)/ET(3x3) gt 0.9
• Real detector
• Due to hot/noisy channel (for example)
• Topological cuts
• Back to back jet veto for 1st 2nd highest ET
  jets
• 1) no cut, 2) df gt p - 0.5

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MET resolution
reconstructed
h lt 5
n, m excluded
QCD Bins (PT-hat)
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MET Distributions
Invisible Higgs
SUSY
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QCD jets MET RatesGenerated Particle Level
n, m excluded
h lt 5 (n, m excluded)
1Hz
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QCD JetsHeavy Flavor Contribution
heavy flavor fraction
MET
Generated MET
PT hat
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Df for MET gt 50 GeV
Jet1 vs Jet2
MET vs Jet2
80 lt PT lt 120 GeV
380 lt PT lt 470 GeV
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DFJJ cuts and results
- this - - DZ - Higgs
74.7 (96.7) fb QCD Zjj
48.0 (71.8)QCD Wjj job
running EW Zjj 12.8 (14.8) EW
Wjj 8.9 (9.9) (very
preliminary)
Set upper limit on sBR(H?inv)
(A.Nikitenko K.Mazumdar)
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L2 without/with Df(1,2) cut
No Df(1,2) cut
Df(1,2) cut
90 GeV
120 GeV
1Hz
MET Threshold
MET Threshold
10 reduction in rate with Df(1,2) cut
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L2 (no Df(1,2) cut) vs L1
L2
L1
1Hz
MET HLT Threshold
MET L1 Threshold
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mSUGRA1
Trigger rates with 95 efficiency as a fucc
of generated MET
1kHz
1Hz
Generated MET
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Invisible Higgs
Trigger rates with 95 efficiency as a
function of generated MET
Generated MET
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Alternative HLT for Invisible Higgs
(A.Nikitenko)
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Summary

• L2 MET Thresholds for 1Hz are
• 120GeV without Df(1,2) cut
• 90GeV with Df(1,2) cut
• Need to implement MET energy scale correction
  with jet correction
• Need to understand source of difference in L2 and
  L1 MET resolution.
• Continue to look for algorithm to lower the MET
  threshold by
• Additional topological cuts
• Improving MET resolution

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Additional Slides
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MET
Multi-jets and MET will provide discovery of
SUSY. How to measure SUSY parameters? ?
need a lot of work. By the way
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Jets
Et of 1st 2nd highest Et jets
Jet Multiplicity (Etgt40GeV)
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Dijet Mass Resolution
With pileup
No pileup
W(jj)
Top(jjj)
Before correction
M(bb) in WH
15
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After correction
Jet energy correction without 19
with 14 CMSJET 15
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(V.Drollinger)
(R.Kinunnen)
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.
A.Nikitenko (Talk on Wednesday)
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MET
Out of cone corr. uses weights for jet(30GeV)
corr.
Corrections Type 1 Jet corr. Type
2 Jet corr. out of cone corr.
(Nikitenko)
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Corrected MET for mSUGURA JetsMET at low lumi
s
Mean offset
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Higgs mass in bbA, A?2t?2j
(A.Nikitenko)
before correction
after correction
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Jet Cone Size
particle-jets vs. reco-jets
Resolution of Mass(Z?jj) - 1994 study -
No min-bias overlap
ISAJET 6.36 Parameterized Simu.
h0.0-0.3

30 min-bias overlap
40
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No bin-bias overlap
0
h1.8-2.1
.2 .4 .6 .8 1.0 1.2
Cone Size
(Fermilab-FN-626)

• Larger R is better for di-jets _at_ low luminosity.
• Need to test with multi jets.
• _at_ high luminosity

(Vardanian/Kodolova)
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Effect of Thresholdon low ET jet and MET
20GeV parton jet _at_ 10E34
MET
(I.Vardanian)
(S.Nikitenko)
Lower threshold is better!
Electronics noise and occupancy define the
threshold. gtgt aim at 0.5GeV/tower _at_ 10E34