Update on Lepton+Jets+MET mSUGRA LM-1: Systematic Uncertainty Decomposition

16.09.2005 R. Cavanaugh, SUSY/BSM Working Group Meeting

1

Update on Lepton+Jets+METmSUGRA LM-1:

Systematic Uncertainty Decomposition

Rick & Bobby


2

Motivating Example:MET (uncorr) From Towers

Total BackgroundLM-1 Signal

Eve

nts

MET [GeV]

Rapidly falls

Flatter

Since this is a Counting Experiment,look at cumulative events passing cuts…

HLT Applied


3

Motivating Example:MET (uncorr) From Towers

Total BackgroundLM-1 Signal

Cu

mu

lati

ve N

um

. E

ven

ts P

assi

ng

Cu

t

Cut on MET [GeV]

Rapidly falls: - B / MET large

Flatter:S / MET small

Naïve expectation:Small systematic effectsaffecting MET might lead to large differences in S / S+B


4

Uncertainty Definitionsconsidered so far…

• Statistical:• S+B

• Systematical:– Finite MC Statistics

• NW / Ngen

– QCD level (not shape)• 50%

– Jet Energy Scale• 10% ET• (affects also MET)

– Jet Energy Resolution• Additional one ET

smearing (ET taken from the DAQ TDR)

• (affects also MET)

• For Jet Systematics

– N = number of events passing cuts before systematic effect applied

– Nsyst = number of events passing cuts after systematic effect applied

– Uncertainty [number of events]:

B = N – Nsyst


5




• NW / Ngen










B = N – Nsyst

Quick side remark:10% seems conservative for this study (we assumes 10 fb-1)

Plan to vary JES systematic according to expected dependence on integrated luminosity

8-10% for L < 1fb-1~3% at some point after 1fb-1


6




• NW / Ngen










B = N – Nsyst

Quick side remark:10% seems conservative for this study (we assumes 10 fb-1)

Plan to vary JES systematic according to expected dependence on integrated luminosity

8-10% for L < 1fb-1~3% at some point after 1fb-1

Many systematics

not yet c

onsidered

(PDFs, m

uon ID eff,

etc)


7

Systematic UncertaintyDecomposition

Statistical MC StatisticsQCDJet E ScaleJet E ResolutionTotal

Un

cert

ain

ty [

nu

mb

er o

f ev

ents

]

Cut on MET [GeV]

HLT Applied


8

Toy “Significance” Decomposition

• Statistical only– S / S + B

• Statistical + MC Statistics– S / S + B + BMC

2

• Statistical + QCD level– S / S + B + 0.5BQCD

• Statistical + Jet Energy Scale– S / S + B + BJES

2

• Statistical + Jet Energy Resolution– S / S + B + BRES

2

• Total– S / S + B + BMC

2 + 0.5BQCD + BJES2 + BRES

2

NOTE: The following plots have HLT applied, MET cuts applied

NO OTHER CUTS APPLIED! significant optimisation still possible (likely)


9

Toy “Significance” DecompositionStatistical onlyStatistical + MC StatisticsStatistical + QCDStatistical + Jet E ScaleStatistical + Jet E ResolutionTotal

“Sig

nif

ican

ce”

Cut on MET [GeV]

HLT Applied

HLT applied,MET cuts applied

NO OTHER CUTS APPLIED! significant optimisation still possible (likely)

Inclusion of different systematics tend to prefer higher MET cut values


10

Observations

• Systematics in toy “significance” definition:– Shift to higher MET cut values preferred– Overall reduction in toy “significance” estimation

• JetMET Uncertainties – Current choices dominate (no JetMET recommendation yet)

• Jet Energy Scale: 10% ET• Jet Energy Resolution: additional one unit of ET

smearing

• Finite MC Statistics Uncertainty– Important, but does not currently dominate!!

• Finite MC Statistics: NW / Ngen

• QCD Level (not-shape) Uncertainty – Not important compared with others (but, prob. too optimistic)

• QCD level: 50%


11

Conclusion• Everything still very preliminary!

– Healthy discussion about Finite MC Statistics Systematic arising from 06 Sept. SUSY/BSM Meeting

• Selection optimisation underway…– Toy “significance” estimate currently being used

• Inclusion of systematic effects being studied– Likelihood ratio method being implemented

• Will be used for final results• Early observations suggest that

– Systematics can have a strong effect– JetMET systematics are important to understand and correctly

estimate• Current assumptions may be conservative? • Need official recommendation from JetMET assuming 10 fb-1 data

collected • We are still collecting additional statistics

– Y. Pakhotin has produced trees for all available ttbar!– We are working to include more W+jets– Will include Alpgen samples when available

Update on Lepton+Jets+MET mSUGRA LM-1: Systematic Uncertainty Decomposition

Documents

Transcript of Update on Lepton+Jets+MET mSUGRA LM-1: Systematic Uncertainty Decomposition