Udine -- June 14, 2006 Ph.D. Thesis Defense 1
Search for Chargino and Search for Chargino and Neutralino production in Neutralino production in
the trilepton channel with the trilepton channel with the CDF Run II detectorthe CDF Run II detector
Melisa RossiUdine University
Ph.D. Thesis DefenseUdine – June 14, 2006
Udine – June 14, 20062Ph.D. Thesis Defense
ContentsContents SupersymmetrySupersymmetry The trilepton signatureThe trilepton signature The CDF detectorThe CDF detector The CDF trigger systemThe CDF trigger system The SUSY DILEPTON triggerThe SUSY DILEPTON trigger
Monitoring & EfficienciesMonitoring & Efficiencies Trilepton analysis @ CDFTrilepton analysis @ CDF
The approachThe approach The eThe eμμ low p low pTT channel channel
CDF Run II Limit on chargino massCDF Run II Limit on chargino mass Conclusions and outlookConclusions and outlook
The Physics Subject
The Tools
The Search
In conclusion
Udine – June 14, 20063Ph.D. Thesis Defense
The Physics Subject
Udine – June 14, 20064Ph.D. Thesis Defense
SupersymmetrySupersymmetry Extends the Standard Extends the Standard
Model (SM) by adding a Model (SM) by adding a new spin symmetrynew spin symmetry boson ↔ fermionboson ↔ fermion SUSY more than doubles SUSY more than doubles
SM particle spectrum SM particle spectrum SUSY naturally solves open SUSY naturally solves open
SM issues providingSM issues providing a framework for a framework for
unificationunification a dark matter candidatea dark matter candidate
No evidence of SUSY yetNo evidence of SUSY yet must be a broken symmetrymust be a broken symmetry
Udine – June 14, 20065Ph.D. Thesis Defense
SupersymmetrySupersymmetry SUSY breaking mechanism SUSY breaking mechanism
determines phenomenology determines phenomenology determines search strategy at collidersdetermines search strategy at colliders mSUGRA is our benchmark modelmSUGRA is our benchmark model
only 5 free parametersonly 5 free parameters
RR-parity-parity additional quantum numberadditional quantum number RRpp = (-1) = (-1) 3(B-L)+2s3(B-L)+2s
RRpp conservation leads to conservation leads to SUSY particles are pair producedSUSY particles are pair produced lightest super particle (LSP) stablelightest super particle (LSP) stable
m0: common scalar mass at GUT scalem1/2: common gaugino mass at GUT scaletan β: ratio of Higgs vacuum expectation valuesA0: trilinear couplingSign(μ): sign of Higgs mass term
m0: common scalar mass at GUT scalem1/2: common gaugino mass at GUT scaletan β: ratio of Higgs vacuum expectation valuesA0: trilinear couplingSign(μ): sign of Higgs mass term
Udine – June 14, 20066Ph.D. Thesis Defense
SUSY cross sections are small!SUSY cross sections are small!
TevatronTevatron
Cro
ss s
ecti
on
s (
pb
)
m (GeV)
Concentrating on chargino and neutralino
Concentrating on chargino and neutralino
100 events per fb-1100 events per fb-1
σσ(SUSY) (SUSY) ~ ~ pb while pb while
σσ((pp) pp) ~ 50 x 10~ 50 x 1099 pb pb
σσ(SUSY) (SUSY) ~ ~ pb while pb while
σσ((pp) pp) ~ 50 x 10~ 50 x 1099 pb pb _
Udine – June 14, 20067Ph.D. Thesis Defense
Chargino & NeutralinoChargino & Neutralino
Mixture of SUSY partners of W, Z, photon, HiggsMixture of SUSY partners of W, Z, photon, Higgs Production & DecayProduction & Decay
+interfering t-channel squark exchange diagrams
FINAL STATE3 isolated leptons
+missing energy
FINAL STATE3 isolated leptons
+missing energy
TevatronGOLDEN
signature
TevatronGOLDEN
signature
Udine – June 14, 20068Ph.D. Thesis Defense
Multilepton Final StatesMultilepton Final States
Multi-lepton signaturesMulti-lepton signatures appealing for other SUSY appealing for other SUSY
searchessearches RPV SUSY processes RPV SUSY processes
very cleanvery clean particularly powerful @ particularly powerful @
hadron colliders where QCD hadron colliders where QCD background dominates background dominates
but leptons from chain but leptons from chain decaysdecays
relatively lowrelatively low p pTT ((< 20 < 20 GeVGeV/c/c))
1 pb
Udine – June 14, 20069Ph.D. Thesis Defense
The Tools
Udine – June 14, 200610Ph.D. Thesis Defense
The Tevatron AcceleratorThe Tevatron Accelerator
CDFCDF
DODO
Udine – June 14, 200611Ph.D. Thesis Defense
The CDF Run II DetectorThe CDF Run II Detector Multipurpose DetectorMultipurpose Detector
precision trackingprecision tracking good calorimeter & good calorimeter & μμ coveragecoverage
Electrons Electrons ||ηη| < 3.6| < 3.6 Muons Muons ||ηη| <1.5| <1.5
Multipurpose DetectorMultipurpose Detector precision trackingprecision tracking good calorimeter & good calorimeter & μμ coveragecoverage
Electrons Electrons ||ηη| < 3.6| < 3.6 Muons Muons ||ηη| <1.5| <1.5
Udine – June 14, 200612Ph.D. Thesis Defense
CDF Trigger SystemCDF Trigger System
RateRate Cross Cross Section Section
L1L1 25 kHz25 kHz 250 250 μμbb
L2L2 300 Hz300 Hz 3 3 μμbb
L3L3 75 Hz75 Hz 750nb750nb
@1E32cm–2s–1
CDF Detector
L1 pipeline5.5μs
L1 pipeline5.5μs
L2 decision20μs
L2 decision20μs
L3 decision600ms
L3 decision600ms
7.6 million events/sec
25kHz
300Hz
75Hz
OFFLINE
3-level architecture 3-level architecture to minimize deadtimeto minimize deadtime
path = unique combination of L1,L2,L3path = unique combination of L1,L2,L3 accept rates are 10x higher than RunIaccept rates are 10x higher than RunI L1+L2 rejection factor is 20000:1L1+L2 rejection factor is 20000:1
Udine – June 14, 200613Ph.D. Thesis Defense
Leptons @ Trigger LevelLeptons @ Trigger Level
CMU4
CMUP4
CMX4
Muon/Electron @ Trigger LevelMuon/Electron @ Trigger Level Muon = track compatible with mip matched to stubMuon = track compatible with mip matched to stub
stub = set of hits in muon chamberstub = set of hits in muon chamber Electron = track matched toElectron = track matched to em deposition in calorimeterem deposition in calorimeter
CEM4
CEM8
PEM8
forward medium
low central
T
T
p
p
forward medium
low central
T
T
p
pELECTRONSELECTRONS
forward tight
loose central
forward tight
loose central
MUONSMUONS
Udine – June 14, 200614Ph.D. Thesis Defense
DILEPTON triggerDILEPTON trigger
inclusive low inclusive low ppTT lepton trigger lepton trigger
not feasible, thennot feasible, then DILEPTON triggerDILEPTON trigger
(electrons and muons)(electrons and muons) highly redundanthighly redundant ( (~20 trigger paths~20 trigger paths))
maximize acceptance (geometry and efficiency)maximize acceptance (geometry and efficiency) easier to understand trigger easier to understand trigger
comparisons between paths comparisons between paths
calibration and monitoring samples in the same data setcalibration and monitoring samples in the same data set extraction of unbiased lepton samplesextraction of unbiased lepton samples detector conditions naturally folded indetector conditions naturally folded in
CDF Total DILEPTON
L2 3000 nb 700 nb
L3 750 nb 80 nb@1E32cm–2s–1
Trigger Cross Section
Udine – June 14, 200615Ph.D. Thesis Defense
DILEPTON trigger layoutDILEPTON trigger layout
A.A. baseline - workhorsebaseline - workhorseB.B. to recover stub/cluster to recover stub/cluster
inefficiencyinefficiencyC.C. to increase the acceptanceto increase the acceptance
A B C
L1L2
2 Low-pT leptons
Medium-pT lepton+track
High-pT
inclusive lepton
L3 2 Low-pt leptons
20 trigger paths
CEM4_CMU4CEM4_CMU4 CEM4_CMUP4CEM4_CMUP4 CEM4_CMX4CEM4_CMX4 ............ CEM4_CMX4_L2_CEM8_TRK8CEM4_CMX4_L2_CEM8_TRK8 CEM4_CMU4_L2_CEM8_TRK8CEM4_CMU4_L2_CEM8_TRK8 .............. CEM4_CEM4_L2_CEM12CEM4_CEM4_L2_CEM12 CEM_PEM8_L2_CEM12CEM_PEM8_L2_CEM12
AA
BB
CC
Udine – June 14, 200616Ph.D. Thesis Defense
DILEPTON trigger strategyDILEPTON trigger strategy
define lepton typesdefine lepton types do not depend on the specific pathdo not depend on the specific path
trigger studies for each lepton typetrigger studies for each lepton type combine single lepton type results into trigger pathscombine single lepton type results into trigger paths
20 trigger paths 6 lepton types6 lepton types
Monitoring & Efficiency Calculation for each lepton type
Monitoring & Efficiency Calculation for each lepton type
CEM4
CEM8
PEM8
CMU4
CMUP4
CMX4
Udine – June 14, 200617Ph.D. Thesis Defense
MonitoringMonitoring defining a suitable variable defining a suitable variable
for each lepton typefor each lepton type
sort of puritysort of purity expected to be stable in timeexpected to be stable in time also different estimationsalso different estimations
for each lepton typefor each lepton type provide cross checks provide cross checks
between pathsbetween paths
events of #
lepton tedreconstruc with events of #R events of #
lepton tedreconstruc with events of #R
4 GeV Central Electron
change in trigger for ET calculation
steps in distributions indicatives of trigger changes
Run NumberRun Number
RC
EM
4R
CE
M4
Udine – June 14, 200618Ph.D. Thesis Defense
Efficiency CalculationEfficiency Calculation
Calculated efficiency for L1 L2 electron lepton typesCalculated efficiency for L1 L2 electron lepton types Used conversion electrons as probeUsed conversion electrons as probe
must satisfy ID cutsmust satisfy ID cuts must be unbiased for the trigger being calibratedmust be unbiased for the trigger being calibrated must come from a conversionmust come from a conversion
each electron associated with a track each electron associated with a track
((||ΔΔcotcotθθ|<0.15 , S|<0.15 , Sxyxy<0.1<0.1))
e+e-
γ
CENTRAL FORWARD
Calorimeter & Tracking
Calorimeter only CENTRAL FORWARD
Udine – June 14, 200619Ph.D. Thesis Defense
The Search
Udine – June 14, 200620Ph.D. Thesis Defense
LOOK at DATA in the SIGNAL REGION
The “signal” region is investigated in data
only at the very end of the analysis
Kinematic regions where
New Physics expected to be small
Analysis approachAnalysis approachSTATISTICALLY UNBIASED
ANALYSIS performed as a COUNTING
EXPERIMENT
Characterization of the signallooking at MC only
Verify the SM backgrounds comparing data vs. MC in
“control regions”
compare number of predicted and observed events
Udine – June 14, 200621Ph.D. Thesis Defense
I. several channels to maximize the acceptance
II. backgrounds III. the analysis selection
I. several channels to maximize the acceptance
II. backgrounds III. the analysis selection
Characterization of the signal
Udine – June 14, 200622Ph.D. Thesis Defense
Leading leptonNext-to-leading leptonThird lepton
I. Analyses @ CDFI. Analyses @ CDF
Many analyses to maximize Many analyses to maximize the acceptancethe acceptance 3 leptons3 leptons 2 leptons + track2 leptons + track 2 leptons with like sign (LS)2 leptons with like sign (LS)
CHANNELCHANNEL LUM (pbLUM (pb-1-1)) TRIGGER PATHTRIGGER PATH
LS ee, eLS ee, e, , 710710 High pHigh pTT Single Lepton Single Lepton
+ e/+ e/ 750750 High pHigh pTT Single Lepton Single Lepton
ee + e/ee + e/ 350350 High pHigh pTT Single Lepton Single Lepton
+ e/+ e/ 310310 Low pLow pTT Dilepton Dilepton
ee + trackee + track 610610 Low pLow pTT Dilepton Dilepton
e + e/ 310 Low pT Dilepton
Leading lepton pT > 20 GeV/c
Leading lepton pT > 10 GeV/c
Udine – June 14, 200623Ph.D. Thesis Defense
This thesis focuses onThis thesis focuses on Events with at leastEvents with at least
1 identified electron and 1 identified muon1 identified electron and 1 identified muon
CEM4CEM4__CMUP4 trigger pathCMUP4 trigger path part of the SUSY DILEPTON triggerpart of the SUSY DILEPTON trigger central electron |central electron |ηη|<1.1 and central muon ||<1.1 and central muon |ηη|<0.6|<0.6 224 pb224 pb-1-1 collected between 2002 and 2004 collected between 2002 and 2004
The The eeμμ channel has l channel has low SM backgroundsow SM backgrounds Heavy flavour and diboson productionHeavy flavour and diboson production Fakes contribution becomes more important than Fakes contribution becomes more important than
in other analysesin other analyses
But low statisticsBut low statistics
I. The I. The eeμμ low p low pT T analysisanalysis
Udine – June 14, 200624Ph.D. Thesis Defense
II. BackgroundsII. Backgrounds
Heavy flavour productionHeavy flavour production Leptons have mainly low pLeptons have mainly low pTT Leptons are rarely isolatedLeptons are rarely isolated Missing transverse energy due to neutrinosMissing transverse energy due to neutrinos
Diboson (WZ,ZZ) productionDiboson (WZ,ZZ) production Leptons have high pLeptons have high pTT Leptons are isolatedLeptons are isolated Missing transverse energy due to neutrinosMissing transverse energy due to neutrinos
Drell-Yan production + Drell-Yan production + additional additional leptonlepton Leptons cover a wide range in pLeptons cover a wide range in pTT Small missing transverse energySmall missing transverse energy Low jet activityLow jet activity
SM processes yielding to
eμ final states
SM processes yielding to
eμ final states
Other processes yielding to
eμ final states
Other processes yielding to
eμ final states
Fake leptons Conversion electrons
Fake leptons Conversion electrons
Udine – June 14, 200625Ph.D. Thesis Defense
III. Basic Analysis SelectionIII. Basic Analysis Selection Two lepton preselectionTwo lepton preselection
leading lepton pleading lepton pTT>10 GeV/c>10 GeV/c next-to leading pnext-to leading pTT>5 GeV/c >5 GeV/c
Missing Transverse EnergyMissing Transverse Energy missing Emissing ETT > 15 GeV > 15 GeV
Third Lepton RequirementThird Lepton Requirement third lepton pthird lepton pTT > 5 GeV/c > 5 GeV/c
Udine – June 14, 200626Ph.D. Thesis Defense
Verify the SM backgrounds
in “control regions”
Udine – June 14, 200627Ph.D. Thesis Defense
Control Regions (CR)Control Regions (CR)
CR in terms of missing ET (high, low)
Njet (high, low) number of leptons
2 lepton selection 3 lepton selection
separating events between like sign (LS) and opposite sign
(OS) charge
Additional high statistics CR to test lepton selection ee and μμ events full invariant mass spectrum Z window mass
15 76 106M()
??1510
< 2 > 1 Number of Jets
ME
T
SIGNAL REGIONif 3 leptons
Udine – June 14, 200628Ph.D. Thesis Defense
Control Regions (ee)Control Regions (ee)
15 76 106M()
Udine – June 14, 200629Ph.D. Thesis Defense
Control Regions (Control Regions (μμμμ))
15 76 106M()
Udine – June 14, 200630Ph.D. Thesis Defense
Control Regions (eControl Regions (eμμ))
??1510
< 2 > 1 Number of Jets
ME
T
OSOS
LSLS
2 lepton selection
Udine – June 14, 200631Ph.D. Thesis Defense
Control Regions (eControl Regions (eμμ))
??1510
< 2 > 1 Number of Jets
ME
T
OSOS
LSLS
2 lepton selection
Udine – June 14, 200632Ph.D. Thesis Defense
Control Regions (eControl Regions (eμμ))
??1510
< 2 > 1 Number of Jets
ME
T
OSOS
OSOS
2 lepton selection
Udine – June 14, 200633Ph.D. Thesis Defense
eeμμ low p low pTT analysis status analysis status
The low missing The low missing transverse energy transverse energy region still needs region still needs better understandingbetter understanding
Need more bbbar MCNeed more bbbar MC Possible fakes Possible fakes
underestimationunderestimation Not looked into the Not looked into the
signal region yetsignal region yet
OSOS
LSLS
Udine – June 14, 200634Ph.D. Thesis Defense
Other Trilepton AnalysesOther Trilepton Analyses
ChannelLumi(pb-1)
Total predicted
background
Example SUSYSignal
Obs-erve
d data
LS ee,e, 710 6.801.00
3.180.33
9
+e/ 750 0.640.181.610.2
21
e +e/ 750 0.780.151.010.0
70
ee + e/ 350 0.170.050.490.0
60
+e/ 310 0.130.030.170.0
40
ee+track 610 0.480.070.900.0
91
Good agreement between observed and predicted events
Good agreement between observed and predicted events
LOOKED in the SIGNAL REGION
Udine – June 14, 200635Ph.D. Thesis Defense
Other Trilepton AnalysesOther Trilepton Analyses
Combine all analyses Combine all analyses exclusivelyexclusively
Degenerate slepton masses Degenerate slepton masses scenarioscenario CDF Run II Limit M(1) ~ 127 GeV/c2
D0 RunII limit in a similar D0 RunII limit in a similar scenario scenario M(M(11) ~ 116 GeV/c) ~ 116 GeV/c22
Slepton mixing scenarioSlepton mixing scenario Acceptance worse, Acceptance worse,
no constraint yetno constraint yet
LOOKED in the SIGNAL REGION
SET CHARGINO MASS LIMIT
Udine – June 14, 200636Ph.D. Thesis Defense
Conclusions and OutlookConclusions and Outlook
The trilepton signature is SUSY Golden channel at the The trilepton signature is SUSY Golden channel at the TevatronTevatron
This thesis focuses on eThis thesis focuses on eμμ final states final states Low SM backgrounds BUT low statisticsLow SM backgrounds BUT low statistics Low missing ELow missing ETT region still needs some work region still needs some work
CDF Run II Limit on chargino mass beyond LEP resultsCDF Run II Limit on chargino mass beyond LEP results But model dependentBut model dependent
Want to finish the analysis by end Summer 06Want to finish the analysis by end Summer 06 ……. and be in the publication!. and be in the publication!
4-8 fb4-8 fb-1-1 by the end of RunII will allow to explore by the end of RunII will allow to explore chargino mass up to 250 GeV/cchargino mass up to 250 GeV/c22
In conclusion
Udine – June 14, 200637Ph.D. Thesis Defense
BACKUP SLIDESBACKUP SLIDES
Udine – June 14, 200638Ph.D. Thesis Defense
Analyses OverviewAnalyses Overview
CHANNEL LUM TRIGGER PATH
LS ee,e, 710 High pT Single Lepton
+ e/ 750 High pT Single Lepton
ee + e/ 350 High pT Single Lepton
+ e/ 310 Low pT Dilepton
ee + track 610 Low pT Dilepton
No third lepton requirement=> Higher acceptance
Using eμ only very small backgrounds
Sensitive to taus as 3rd lepton
Udine – June 14, 200639Ph.D. Thesis Defense
mSUGRA mSUGRA “small “small mm00””
MM( ( ) ) > > MM((2200))
No slepton mixingNo slepton mixing
x x BRBR < 0.2 pb < 0.2 pb
mSUGRAmSUGRA “large “large mm00””
MM( ( ) ) ≫≫ MM((2200))
No sensitivityNo sensitivity
~~
Those limits are improved by ~10% if tau’s are included.
A0=0
~~
ScenarioScenario
light sleptons but heavy squarks
M(20) 3M(q)
ScenarioScenario
light sleptons but heavy squarks
M(20) 3M(q)
~~
Fermilab-Pub-05/075-E or hep-ex/0504032
117 GeV/c2
132 GeV/c2
Chargino Mass LimitsChargino Mass Limits
103.5 GeV/c2
(model independent)
Udine – June 14, 200640Ph.D. Thesis Defense
The differences in the modelsThe differences in the models
In StandardmSugra theBR into tausis enhanced
smalleracceptance
Udine – June 14, 200641Ph.D. Thesis Defense
Systematic uncertaintySystematic uncertainty
Major systematic uncertainties affecting the number of events (ee+lepton high pT) Signal
Lepton ID 5% Muon pT resolution 7%
Background Fake lepton estimate method 5% Jet Energy Scale 22%
Both signal and background Luminosity 6% Theoretical Cross Section 6.5-7% PDFs 7%
Udine – June 14, 200642Ph.D. Thesis Defense
TRIGGER PATH LISTTRIGGER PATH LIST1.1. cem4_cmu4cem4_cmu42.2. cem4_cmu4_l2_cem8_pt8_ces2_&_trk8cem4_cmu4_l2_cem8_pt8_ces2_&_trk83.3. cem4_cmu4_l2_trk8_l1_cmup6_pt4cem4_cmu4_l2_trk8_l1_cmup6_pt44.4. cem4_cmup4cem4_cmup45.5. cem4_cmx4cem4_cmx46.6. cem4_cmx4_l2_cem8_pt8_ces2_&_trk8cem4_cmx4_l2_cem8_pt8_ces2_&_trk87.7. cem4_pem8cem4_pem88.8. cem4_pem8_l2_cem12_pt8cem4_pem8_l2_cem12_pt89.9. cem8_pem8cem8_pem810.10. cmu4_pem8 _cmu4_pem8 _11.11. cmu4_pem8_l2_trk8_l1_cmup6_pt4cmu4_pem8_l2_trk8_l1_cmup6_pt412.12. cmup4_pem8 cmup4_pem8 13.13. cmx4_pem8cmx4_pem814.14. dielectron_central_4dielectron_central_415.15. dielectron_central_4_l2_cem12_pt8dielectron_central_4_l2_cem12_pt816.16. dielectron_central_4_l2_cem8_pt8_ces2_&_tdielectron_central_4_l2_cem8_pt8_ces2_&_t
rk8rk817.17. dimuon_cmu4_cmx4dimuon_cmu4_cmx418.18. dimuon_cmu4_cmx4_l2_trk8_l1_cmup6_pt4dimuon_cmu4_cmx4_l2_trk8_l1_cmup6_pt419.19. dimuon_cmucmu4dimuon_cmucmu420.20. dimuon_cmucmu4_l2_trk8_l1_cmup6_pt4dimuon_cmucmu4_l2_trk8_l1_cmup6_pt421.21. dimuon_cmup4_cmx4dimuon_cmup4_cmx422.22. dimuon_cmupcmup4 dimuon_cmupcmup4
1.1. cem4_cmu4cem4_cmu42.2. cem4_cmu4_l2_cem8_pt8_ces2_&_trk8cem4_cmu4_l2_cem8_pt8_ces2_&_trk83.3. cem4_cmu4_l2_trk8_l1_cmup6_pt4cem4_cmu4_l2_trk8_l1_cmup6_pt44.4. cem4_cmup4cem4_cmup45.5. cem4_cmx4cem4_cmx46.6. cem4_cmx4_l2_cem8_pt8_ces2_&_trk8cem4_cmx4_l2_cem8_pt8_ces2_&_trk87.7. cem4_pem8cem4_pem88.8. cem4_pem8_l2_cem12_pt8cem4_pem8_l2_cem12_pt89.9. cem8_pem8cem8_pem810.10. cmu4_pem8 _cmu4_pem8 _11.11. cmu4_pem8_l2_trk8_l1_cmup6_pt4cmu4_pem8_l2_trk8_l1_cmup6_pt412.12. cmup4_pem8 cmup4_pem8 13.13. cmx4_pem8cmx4_pem814.14. dielectron_central_4dielectron_central_415.15. dielectron_central_4_l2_cem12_pt8dielectron_central_4_l2_cem12_pt816.16. dielectron_central_4_l2_cem8_pt8_ces2_&_tdielectron_central_4_l2_cem8_pt8_ces2_&_t
rk8rk817.17. dimuon_cmu4_cmx4dimuon_cmu4_cmx418.18. dimuon_cmu4_cmx4_l2_trk8_l1_cmup6_pt4dimuon_cmu4_cmx4_l2_trk8_l1_cmup6_pt419.19. dimuon_cmucmu4dimuon_cmucmu420.20. dimuon_cmucmu4_l2_trk8_l1_cmup6_pt4dimuon_cmucmu4_l2_trk8_l1_cmup6_pt421.21. dimuon_cmup4_cmx4dimuon_cmup4_cmx422.22. dimuon_cmupcmup4 dimuon_cmupcmup4
Udine – June 14, 200643Ph.D. Thesis Defense
II. Other BackgroundsII. Other Backgrounds
Additional lepton contribution in the event Additional lepton contribution in the event
comes fromcomes from Fake leptonsFake leptons
Fake rates extracted Fake rates extracted
from Inclusive Jet Sample from Inclusive Jet Sample
with different trigger thresoldswith different trigger thresolds
Electron Fake rate per Jet
Jet ET
Udine – June 14, 200644Ph.D. Thesis Defense
Control Regions – SummaryControl Regions – Summary
Udine – June 14, 200645Ph.D. Thesis Defense
L1 Electron PrimitivesL1 Electron Primitives
Trigger RequirementsTrigger Requirements L1 4 GeV Central ElectronL1 4 GeV Central Electron
Calorimeter Trigger TowerCalorimeter Trigger Tower EETT ≥≥ 4 4 GeVGeV EEhad had / E/ Eemem ≤≤ 12.5% 12.5%
TrackTrack PPTT ≥≥ 4 4 GeVGeV/c/c
L1 8 GeV Forward ElectronL1 8 GeV Forward Electron Calorimeter Trigger TowerCalorimeter Trigger Tower
EETT ≥≥ 8 8 GeVGeV EEhad had / E/ Eemem ≤≤ 6.25% 6.25%
em
em
Udine – June 14, 200646Ph.D. Thesis Defense
Probe ElectronsProbe Electrons Must satisfy ID cutsMust satisfy ID cuts Must be unbiased for the Must be unbiased for the trigger being calibratedtrigger being calibrated
i.e. events collected by triggers i.e. events collected by triggers
unrelated to the one testedunrelated to the one tested Must come from a Must come from a
conversionconversion each electron associated each electron associated with a track requiringwith a track requiring
||ΔΔcotcotθθ|<0.15 , S|<0.15 , Sxyxy<0.1<0.1
Consider 2 sub-samplesConsider 2 sub-samples Peak Peak ||ΔΔcotcotθθ|<0.03|<0.03
(Electrons+Fakes) (Electrons+Fakes) Sideband Sideband ||ΔΔcotcotθθ|>0.05|>0.05
(assuming Fakes only)(assuming Fakes only)
e+e-
γ
Udine – June 14, 200647Ph.D. Thesis Defense
L1 Trigger EfficiencyL1 Trigger Efficiency
Central electron efficiency plateau value ~ 90% due to tight track requirement
Forward electron efficiency slow turn-on due to online-offline energy difference
FORWARD
CENTRAL FORWARD
Calorimeter & Tracking
Calorimeter only CENTRAL FORWARD
Udine – June 14, 200648Ph.D. Thesis Defense
Back-up Plug Conversion Back-up Plug Conversion SelectionSelection