Searches for WZ and ZZ Diboson Production in Final States with Jets and Charged Leptons Or Missing Transverse Energy at CDF

Searches for WZ and ZZ Diboson Production in Final States with Jets and Charged Leptons or Missing Transverse Energy at CDF

Wesley Ketchum (University of Chicago) on behalf of the CDF Collaboration 19th Particle and Nuclei International Conference 7/25/2011 Motivation

ν, l− @ @ q¯ ν, l • Semi-hadronic diboson @I Z − @ q¯ @ 6 + decays important step @ @@ ν¯, l @ @ + Z to Higgs @ ν¯, l @I @ Z @ ∗ – Share similar ﬁnal state 6 q @@ 2 @@ for m < 135 GeV/c H ¯ H @@ b

– Testing ground for new q ? @ b tools q Z @ I@ • Previous observations @ q¯ all involve WW ZZ Producon ZH Producon – Larger σ Process Cross Section (pb) WW 11.70 0.7 – Large Wl,ν branching ± ratio WZ 3.60 0.3 ZZ 1.49 ± 0.2 • In this talk ± – WZ/ZZ  lν,νν + qq : MET (Missing transverse energy) + jets • b tagging to separate from WW – ZW/ZZ  l+l- + qq/qqʼ : Charged leptons + jets • New quark-gluon discriminant to combat large Z + (gluon) jets background 1

7/25/11 PANIC11 2

1 Previous Tevatron WZ/ZZ Measurements

Process SM σ (pb) Decay Channel σ (pb) ∫L (Year Pub.) Exp.

+ ‐ +1.07 ‐1 WZ 3.6 lν, l l 3.89 ‐0.90 4.1 (2010) D0

+0.8 ‐1 3.9 ‐0.7 7.1 (2011) CDF

+ ‐ + ‐ +0.49 ‐1 ZZ 1.5 l l , l l 1.26 ‐0.40 6.4 (2011) D0 2.18 ± 0.49 6.1 ‐1 (2011) CDF

l+l‐, νν 2.01 ± 0.97 2.7 ‐1 (2008) D0

+0.60 ‐1 1.45 ‐0.51 5.9 (2010) CDF WZ 3.6 lν,jj & l+l‐,jj ?

ZZ 1.5 νν,jj & l+l‐,jj ?

7/25/11 PANIC11 3 Other New Tevatron Measurements

Process Experiment URL

Wγ D0 hp://www‐d0.fnal.gov/Run2Physics/WWW/results/prelim/ EW/E36/

Zγ CDF hp://www‐cdf.fnal.gov/physics/ewk/2011/zgamma/ Zgamma5inv/index.html W + jj D0 hp://www‐d0.fnal.gov/Run2Physics/WWW/results/ﬁnal/ HIGGS/H11B/ CDF hp://www‐cdf.fnal.gov/physics/ewk/2011/wjj/7_3.html

WW/WZ CDF hp://www‐cdf.fnal.gov/physics/new/hdg/Results_ﬁles/  lν + h.f. results/wzlnubb_071911/

7/25/11 PANIC11 4 About the Tevatron and CDF • Fermilab Tevatron – Collide p-pbar at √s = 1.96 TeV – 11.6 fb-1 delivered to experiments • Collider Detector at Fermilab (CDF) – Silicon detectors and “outer” drift chamber for particle tracking – Electromagnetic and hadronic calorimeters – Muon systems outside calorimeters

7/25/11 PANIC11 5 Event Selection MET + Jets e+e-,μ+μ- + Jets

• Data from MET triggers • Data from high-pT lepton – MET > 50 GeV triggers

– Quality cuts to reduce – Leptonsʼ pT > 20 GeV/c “fake” MET from multijet – 76 GeV/c2 < Dilepton Mass production < 106 GeV/c2 – Determine trigger efﬁciency – Determine trigger efﬁciency from Zμ+μ- sample by comparing data and MC in Z + 1 jet sample

• Two (or more) jets

– Jetsʼ ET > 20 GeV, |η| < 2.0 – Fit to Dijet Mass to extract Diboson signal

7/25/11 PANIC11 6 Artiﬁcial Neural-Network Based Jet bness Tagger • Multivariate algorithm to separate b jets from non-b jets – Long B hadron lifetimes – Large B hadron mass compared to decay products • Focus on properties of individual tracks – Train NN to assign “track bness” to each track in a jet

• Consider d0, z0, pT, rapidity and pT w.r.t. jet axis (p⊥) – Combine with jet-level information to assign overall “jet bness”

• Decay length in xy-plane (Lxy), existence of KS or μʼs in jet

Track bness NN Jet bness Jet bness NN Value Tracks Inside Jet Jet‐Level Info

7/25/11 PANIC11 7 Jet bness Tagger

/01$23&$44$56"7898&:6; *+., !"#$!"%&'( • Train using ZZ Pythia MC *+. !"%&'( :6<8#6:6;$3&8#' – Jets from Zbb decays for *+-, b jet samples *+- *+),

– Jets from Zqq (no bʼs *+)

present) for non-b samples *+*,

* () (*+, * *+, ) !"#$%&"''

• “Tag”: Place cut on minimum CDF Run II Preliminary, !L = 4.8 fb-1 Data ! bness value for jets 400 tt Selection W Z/ZZ W+W- tt - – Optimize cut location Z" l+l +bb - 300 Z" l+l W! ! +bb – Calculate efﬁciency of cut in " # $# ! ! W " " $"+bb ! ! W " e $e+bb

data from b-rich tt selection Events / 0.05 units W! ! 200 " # $# ! ! W " " $" – Get mistag rate from Z or W W!" e!$ + jets samples e 100 – Correct MC efﬁciency/mistag rate to match data 0 -1 -0.5 0 0.5 1 Highest jet bness 7/25/11 PANIC11 8 Artiﬁcial Neural-Network Based Jet Quark-Gluon Discriminant

• WZ/ZZ signal is entirely quark jets – W/Z + jets background has signiﬁcant gluon contribution • Gluon jets more spatially spread than quark jets – Gluons have more color Quark Gluon charge than quarks • Construct distribution of distances between pairs of towers and tracks in a jet – ΔR = [ (Δη)2 + (Δφ)2 ]½ – Weight towers/tracks by their energy/momentum content

A wedge of the CDF central calorimeter. Towers’ size ~ 0.1 in η and 15° in φ. 7/25/11 PANIC11 9 Jet QG Discriminant • Content in bins of ΔR are inputs into NN discriminant – Separate NNs for tower and track distributions Distribution of Towers in Jets Distribution of Tracks in Jets

0.4 CDF Run II Preliminary 0.06 CDF Run II Preliminary Z"!+!- + 2 parton Alpgen MC Z"!+!- + 2 parton Alpgen MC Light Quark Jets Light Quark Jets 0.3 Gluon Jets Gluon Jets

Energy Content 0.04

0.2 Momentum Content

0.02 0.1

0 0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 0 0.2 0.4 0.6 0.8 1 1.2 1.4 ! R Between Tower Pairs ! R Between Track Pairs

Tower Neural Network Output Track Neural Network Output

CDF Run II Preliminary CDF Run II Preliminary Z!!+!- + 2 parton Alpgen MC 0.06 Z!!+!- + 2 parton Alpgen MC 0.06 Light Quark Jets Light Quark Jets Gluon Jets Gluon Jets

0.04 0.04 Events (Normalized) Events (Normalized)

0.02 0.02

0 0 -1.5 -1 -0.5 0 0.5 1 1.5 -1.5 -1 -0.5 0 0.5 1 1.5 NN Output NN Output 7/25/11 PANIC11 10 Jet QG Discriminant

Final QG Neural Network Output • Use third neural network to combine tower and track information, and CDF Run II Preliminary Z!!+!- + 2 parton Alpgen MC other relevant jet variables 0.06 Light Quark Jets Gluon Jets – Tower and Track NN values

0.04 – Ratios of Energy and Momentum in

Events (Normalized) Cone 0.4 to 0.7 around jet

0.02 – Jet EM Fraction – Number of Tracks and Towers in jet

0 -1.5 -1 -0.5 0 0.5 1 1.5 – Jet ET, η Final QG Value • Gluon distribution normalized to match quarks

tt Lepton + Jets Selection: Sum Jet QG – Number of interaction vertices CDF Run II Preliminary !L = 6.6 fb-1 • Calibrate MC response by 80 Data Events / bin Diboson comparing data and MC in W + 1 60 tt Z + b jets jet selection region 40 Z + jets W + b jets • Determine efﬁciency of cut on QG W + jets 20 value

0 -1 -0.5 0 0.5 1 – tt  Wb, Wb  lνb, qqʼb for quark-jet Sum Jet QG signal More Quark‐Like – W + jets for background-like regions 7/25/11 PANIC11 11 Backgrounds To Diboson Searches: W/Z + Jets • Dominant background for both analyses • Two different approaches MET + Jets: Charged Leptons + Jets: Photon + 2 jet data used Use MC, but scale JES of to correct MC modeling of gluon jets down based on dijet mass Z + 1 jet balancing studies

CDF Run II Preliminary, = 6.0 fb-1 Z-Jet Balancing: Jet QG Value 0.2 T 0.18 No-Tag Electroweak MC Template CDF Run II Preliminary, "L = 6.6 fb-1 0.16 / Z P 1.1 Data - Fakes No-Tag !+Jets Data Template T MC, JES 0 0.14 MC, JES -2! (Gluons) 1/N dN/(8 GeV)

Jet E 1.05 MC, JES -1! (All) 0.12

0.1 1

0.08

0.06 0.95

0.04 0.9 0.02 -1 -0.5 0 0.5 1 0 40 60 80 100 120 140 160 2 Jet QG Value Mjj (GeV/c ) 7/25/11 PANIC11 More Quark‐Like 12 Backgrounds To Diboson Searches: Jets Faking Charged Leptons/Neutrinos

• MET + Jets: MET METTrk MET – Multijet production with mismeasured jet energies can fake MET METTrk – To model…

• Construct missing PT from tracks (METTrk) MET and • Δφ(MET,METTrk) > 1 MET and MET  “QCD-Enhanced” Trk METTrk Aligned Not Aligned  region  Real MET Fake MET (from ν) • Lepton + Jets – W + 1 jet faking a lepton may pass dilepton cuts • Use like-sign objects to model muon fakes • Calculate probability of jet to fake electron from jet triggered data

7/25/11 PANIC11 13 3 -1 -1 !10 No-tag Channel / CDF Run II Preliminary, = 5.5 fb 2-tag Channel / CDF Run II Preliminary, = 5.5 fb 40 QCD QCD 160 35 WW WW Single Top 140 Single Top 30 tt 120 tt 25 EWK 100 EWK

Events / 8 GeV Data Events / 8 GeV Data 20 80 15 60 10 40 5 20 0 0 40 60 80 100 120 140 160 40 60 80 100 120 140 160 M [GeV] M [GeV] jj MET + Jets Resultsjj

3 -1 -1 2 !10 No-tag Channel / CDF Run II Preliminary, = 5.5 fb 2-tag Channel / CDF Run II Preliminary, = 5.5 fb • 40 Perform χ ﬁt to WZ+ZZ 180 WZ+ZZ QCD QCD 35 160 WW WW dijet mass in two 30 Single Top 140 Single Top 25 tt 120 tt EWK 100 EWK

Events / 8 GeV Events / 8 GeV channels 20 Data Data 80 15 60 – Heavy-ﬂavor 10 40 5 20 enriched “2-tag” 0 0 40 60 80 100 120 140 160 40 60 80 100 120 140 160 Mjj [GeV] Mjj [GeV] region 1 CDF Run II Preliminary, L =5.5 fb− No-tag Channel / CDF Run II Preliminary, =5.5 fb-1 2-tag Channel / CDF Run II Preliminary, =5.5 fb-1 – Remaining events in 500 Process(es) Fit Nevents (no-tag) Fit Nevents (2-tag) WZ+ZZ ! WZ+ZZ 400 “no-tag” region Standard Model 20 Standard Model 300 EWK 153300 3000 694 48 Data - BGs±+34 ±+13 Data - BGs 200 ¯ 10 tt 517 36 129 15 • Best ﬁt: N ~ Events / 8 GeV 100 − Events / 8 GeV +24− WZ/ZZ 0 single t 1180 130 0 183 26 ± − SM prediction -100 QCD 72300 2800 -10 54.6 7.3 -200 ± ±+1.8 -300 WW 2720 190 8.3 -20 1.9 • Use Feldman- 40 60 80 100 120 140± 160 40 60 − 80 100 120 140 160 WZ/ZZ 1160M [GeV]620 39.9 20 M [GeV] jj± ± jj Cousins method to 1 CDF Run II Preliminary, L =5.5 fb− extract sensitivity Process(es) Fit Nevents (no-tag) Fit N!events (2-tag) EWK 153300 3000 694 48 ± ± ¯ +24 tt and single t 1700 140 313 26 +3.6 ± − σ = 5.0 pb QCD 72300 2800 54.6 7.3 WZ/ZZ ‐2.5 ± ±+1.8 WW 2720 190 8.3 1.9 < 13 pb at 95% CL ± − WZ/ZZ 1160 620 39.9 20 ± ±

7/25/11 PANIC11 14 Charged Leptons + Jets Results CDF Run II Preliminary, ! L = 6.6 fb-1 Heavy Flavor Tag Channel Light Flavor Tag Channel No-Tag Channel • Perform χ2 ﬁt to dijet

2 2 600 2 100 WZ+ZZ WZ+ZZ 800 WZ+ZZ Z+jets Z+jets Z+jets mass in three WW WW WW 80 tt tt 600 tt channels 400 Fakes Fakes Fakes 60 Events / 10 GeV/c Data Events / 10 GeV/c Data Events / 10 GeV/c Data 400 – Heavy-ﬂavor tag

40 200 region using jet bness 200 20 – Light-ﬂavor tag region 0 0 0 50 100 150 200 50 100 150 200 50 100 150 200 2 2 2 MJJ (GeV/c ) MJJ (GeV/c ) MJJ (GeV/c ) using jet QG

2 Observed Signal 2 Observed Signal 2 Observed Signal – Remaining events in 100 Expected Signal 60 Expected Signal Expected Signal 20 Data - Background Data - Background Data - Background no-tag region

40 10 50

Events / 10 GeV/c Events / 10 GeV/c Events / 10 GeV/c • Best Fit: N = 0 20 0 WZ/ZZ 0 0 -10 • Use Feldman-Cousins

-20 -20 -50 method to get limit

50 100 150 200 50 100 150 200 50 100 150 200 M (GeV/c2) M (GeV/c2) M (GeV/c2) JJ JJ JJ – σSM consistent with no CDF Run II Preliminary, L =6.6 fb-1 observed signal Process Nevents (HF Tag) Nevents (LF Tag) Nevents! (No Tag) +170 +920 +1300 Z + jets 660 150 3900 800 5800 1800 −+0.56 +0− .19 +0− .42 tt¯ 4.26 0.59 0.86 0.23 2.51 0.36 − +0− .07 +0− .07 WW 0.025 0.002 0.26 0.04 0.56 0.19 σWZ/ZZ < 1.3 x σSM (Exp: 2.3) Fakes 18.3± 4.7 80 − 21 190 − 49 +3±.3 +17± +16± W Z/ZZ 0at limit 0at limit 0at limit < 6.6 pb at 95% CL Data 685 26 3942 63 5976 77 ± ± + ± W Z/ZZ l l−jj Search → 7/25/11 PANIC11 15 Conclusions • Have conducted searches for WZ/ZZ production in semi- hadronic final states 2 – Similar final state to Higgs searches with mH < 135 GeV/c • Using new multivariate algorithms to increase sensitivity – Jet bness tagger picks out heavy-flavor jets – Jet QG discriminant separates light-flavor quark jets from gluon jets • Extract signal through fit to dijet mass distribution -1 – MET + jets: σWZ/ZZ < 13 pb at 95% CL (5.5 fb ) -1 – Charged leptons + jets: σWZ/ZZ < 6.6 pb at 95% CL (6.6 fb )

• Standard model: σWZ/ZZ = 5.1 pb • Looking ahead – Further studies of W/Z + jets modeling using jet QG value • Reduce systematic uncertainties on modeling – Implement new tools in Higgs searches

7/25/11 PANIC11 16 BACKUP SLIDES

7/25/11 PANIC11 17 Jet bness Tagger: Efﬁciency and Mistag Rates

CDF Run II Preliminary, !L = 4.8 fb-1 CDF Run II Preliminary, !L = 4.8 fb-1 104 Data Data W!Z/ZZ 400 W!Z/ZZ Z + 1 jet Selection tt Selection + - W+W- W W tt tt 3 + - 10 + - Z" l l +bb Z# " " +bb + - Z + -+bb 300 Z" l l # " " ! ! + - W " # $#+bb Z# e e +bb ! ! + - W " " $"+bb Z# " " ! ! 2 + - W " e $e+bb Events / 0.05 units 10 Z Events / 0.05 units # " " W! ! + - 200 " # $# Z# e e ! ! W " " $" ! ! W " e $e 10 100

1 0 -1 -0.5 0 0.5 1 -1 -0.5 0 0.5 1 Jet bness Highest jet bness

CDF Run II Preliminary, !L = 4.8 fb-1 CDF Run II Preliminary, !L = 4.8 fb-1 104 Data Data Z + 1 jet Selection All MC 400 tt Selection All MC b jet MC b jet MC 103

300 102

Events / 0.05 units 10 Events / 0.05 units 200

1 100 10-1

10-2 0 -1 -0.5 0 0.5 1 -1 -0.5 0 0.5 1 Jet bness Highest jet bness 7/25/11 PANIC11 18 Jet bness Tagger: Efﬁciency and Mistag Rates

CDF Run II Preliminary, !L = 4.8 fb-1 CDF Run II Preliminary, !L = 4.8 fb-1 Data Data ! 300 W Z/ZZ 300 All MC tt Selection + - tt Selection W W b jet MC tt - Z" l+l +bb - Z" l+l ! ! W " # $#+bb 200 ! ! 200 W " " $"+bb ! ! W " e $e+bb Events / 0.05 units ! ! Events / 0.05 units W " # $# ! ! W " " $" ! ! W " e $e 100 100

0 0 -1 -0.5 0 0.5 1 -1 -0.5 0 0.5 1 2nd highest jet bness 2nd highest jet bness

7/25/11 PANIC11 19 Jet bness Tagger: Efﬁciency and Mistag Rates

-1 -1 CDF Run II Preliminary, L = 4.8 fb CDF Run II Preliminary, !L = 4.8 fb 1 ! 1 Data Data Uncertainties Uncertainties 0.8 Monte Carlo 0.8 Monte Carlo Efficiency Efficiency

0.6 0.6

0.4 0.4

0.2 0.2

0 0 -0.2 -0.1 0 0.1 0.2 0.5 0.6 0.7 0.8 0.9 1 Jet bness cut Jet bness cut

-1 CDF Run II Preliminary, !L = 4.8 fb CDF Run II Preliminary, L = 4.8 fb-1 0.05 0.15 ! Data Data

Uncertainties Uncertainties Monte Carlo 0.04 Monte Carlo

Mistag Rate Mistag Rate 0.1 0.03

0.02 0.05

0.01

0 0 0.5 0.6 0.7 0.8 0.9 1 -0.2 -0.1 0 0.1 0.2 Jet bness cut Jet bness cut

7/25/11 PANIC11 20 Jet QG Discriminant: Flow Chart

!"#$%"&'()*+),+ !"#$%"&'()*+),+ -)./%#+ -%012#+

7$8/%+9/$+ :*,)%;0()*+ -)./%+3/'%04+ 3/$.)%2+ -%012+33+ 5336+

<"*04+=>+33+ !"#1%";"*0*$+

7/25/11 PANIC11 21 Jet QG Discriminant: Efﬁciency/Mistag Rates

tt Dilepton Selection: Sum Jet Bness W + 2 Jet Selection: Jet Sum bness

500 CDF Run II Preliminary CDF Run II Preliminary 4 -1 !L = 6.6 fb-1 10 !L = 6.6 fb Data 400 Data Events / bin Events / bin Diboson Fakes 103 WZ+ZZ tt 300 WW Z + b jets 2 Z + jets tt 10 200 Z + b jets W + b jets Z + jets W + jets 100 10

0 -1 -0.5 0 0.5 1 -1 -0.5 0 0.5 1 Sum Jet Bness Jet Sum bness

tt Lepton + Jets Selection: Sum Jet QG W + 2 Jet Selection: Sum Jet QG Value CDF Run II Preliminary -1 !L = 6.6 fb CDF Run II Preliminary 2000 -1 80 !L = 6.6 fb Data Data Events / bin Events / bin Diboson 1500 Diboson 60 tt tt Z + b jets Z + b jets 40 Z + jets 1000 Z + jets W + b jets W + b jets W + jets W + jets 20 500

0 0 -1 -0.5 0 0.5 1 -1 -0.5 0 0.5 1 Sum Jet QG Sum Jet QG Value

7/25/11 PANIC11 22 Z-Jet Balancing: Jet QG Value T CDF Run II Preliminary, "L = 6.6 fb-1 / Z P 1.1 Data - Fakes T MC, JES 0 MC, JES -2! (Gluons)

Jet E 1.05 MC, JES -1! (All)

0.95

0.9

-1 -0.5 0 0.5 1

Jet QG Value

7/25/11 PANIC11 23 Z-Jet Balancing: Jet ! 1.15 T CDF Run II Preliminary, #L = 6.6 fb-1 / Z P Data - Fakes T 1.1 MC, JES 0 MC, JES -2" (Gluons)

Jet E MC, JES -1" (All) 1.05

0.95

0.9

-2 -1 0 1 2

Jet !

7/25/11 PANIC11 24 Z-Jet Balancing: Jet E T T 1.1 / Z P T

1 Jet E

0.9

CDF Run II Preliminary, "L = 6.6 fb-1 0.8 Data - Fakes MC, JES 0 MC, JES -2! (Gluons) MC, JES -1! (All) 0.7

20 40 60 80 100 120

Jet ET

7/25/11 PANIC11 25 Flow Chart for Analysis

!"#"$"%&'"(&)&*+,-"

!"#$ ./00"12" %&$ 3/45"

./00";<" !"#$ 3/45" %&$

1263/4" 9263/4" :,63/4" 78/--&)" 78/--&)" 78/--&)"

7/25/11 PANIC11 26 Z + 2 Jet Selection: Tagging Variables

Z + 2 Jet Selection: Sum Jet bness Z + 2 Jet Selection: Sum Jet QG Value

104

CDF Run II Preliminary CDF Run II Preliminary !L = 6.6 fb-1 800 !L = 6.6 fb-1 103 Data Data Events / bin Events / bin Fakes 600 Fakes WZ+ZZ WZ+ZZ 102 WW WW tt 400 tt 10 Z + b jets Z + b jets Z + jets Z + jets 200

0 -1 -0.5 0 0.5 1 -1 -0.5 0 0.5 1 Sum Jet bness Sum Jet QG Value

Z + 2 Jet Selection: Sum Jet bness Z + 2 Jet Selection: Sum Jet QG Value 1 0.1 CDF Run II Preliminary!L = 6.6 fb-1 CDF Run II Preliminary!L = 6.6 fb-1 Data 0.08 Data

10-1 Expectation Expectation 0.06

0.04 10-2 Events / bin (Normalized) Events / bin (Normalized)

0.02

10-3 0 -1 -0.5 0 0.5 1 -1 -0.5 0 0.5 1 Sum Jet bness Sum Jet QG Value

7/25/11 PANIC11 27 Charged Leptons + Jets: Expected Events

CDF Run II Preliminary, L =6.6 fb-1 Process Nevents (HF Tag) Nevents (LF Tag) Nevents! (No Tag) +550 +970 Z + jets 730 120 3510 630 5490 1120 ±+0.56 +0− .19 +0− .42 tt¯ 4.26 0.59 0.86 0.23 2.51 0.36 − +0− .07 +0− .07 WW 0.025 0.002 0.26 0.04 0.56 0.19 Fakes 18.9± 4.7 82 − 21 196 − 49 ±+120 ±+550 ±+970 Total Background 760 130 3600 620 5690 1120 −+2.0 +9− .7 −+9.6 W Z/ZZ 15.9 2.1 87.2 9.4 80.3 9.2 +120− −+560 +980− Total Predicted 770 130 3690 630 5770 1120 Data 685 − 26 3942 − 63 5976 − 77 ± ± + ± W Z/ZZ l l−jj Search →

7/25/11 PANIC11 28 Z + 2 Jet Selection: Dijet Mass Fit Templates

Z + 2 Jet Selection: Dijet Mass (LF Tag Region) Z + 2 Jet Selection: Dijet Mass (HF Tag Region) 2 2 100 CDF Run II Preliminary CDF Run II Preliminary 500 L = 6.6 fb-1 -1 ! !L = 6.6 fb Data 80 Data 400 Fakes Fakes WZ+ZZ 60 WZ+ZZ 300 Events / 10 GeV/c WW Events / 10 GeV/c WW tt tt 40 200 Z + b jets Z + b jets Z + jets Z + jets 20 100

0 0 50 100 150 200 50 100 150 200 2 2 MJJ (GeV/c ) MJJ (GeV/c )

Z + 2 Jet Selection: Dijet Mass (HF Tag Region) Z + 2 Jet Selection: Dijet Mass (LF Tag Region)

0.15 0.15 CDF Run II Preliminary!L = 6.6 fb-1 CDF Run II Preliminary!L = 6.6 fb-1 Data Data Expectation Expectation

(Normalized) 0.1 (Normalized) 0.1 2 2

0.05 0.05 Events / 10 GeV/c Events / 10 GeV/c

0 50 100 150 200 50 100 150 200 2 2 MJJ (GeV/c ) MJJ (GeV/c )

7/25/11 PANIC11 29 Z + 2 Jet Selection: Dijet Mass Fit Templates

Z + 2 Jet Selection: Dijet Mass (No Tag Region) Z + 2 Jet Selection: Dijet Mass (No Tag Region) 2 800 CDF Run II Preliminary 0.14 -1 !L = 6.6 fb CDF Run II Preliminary!L = 6.6 fb-1 0.12 600 Data Data Fakes 0.1 Expectation (Normalized) WZ+ZZ 2 0.08 Events / 10 GeV/c 400 WW tt 0.06 Z + b jets 0.04 200 Z + jets

0.02 Events / 10 GeV/c

0 0 50 100 150 200 50 100 150 200 2 2 MJJ (GeV/c ) MJJ (GeV/c )

7/25/11 PANIC11 30 Remaining Backgrounds

• Backgrounds – Top quark production • Add cuts to reduce top-pair production background – MET + jets: cuts on jet and lepton multiplicty – Leptons + jets: Require MET < 25 GeV – WW diboson production (MET + jets) • Indistinguishable from signal (WZ/ZZ) from dijet mass • Use b tagging to pick out events with Zbb

7/25/11 PANIC11 31 MET + Jets: Multijet Production Modeling

MET Quality Cuts in QCD dijet mass distribuon in MET + Jets Analysis MET + Jets Analysis -1 -1 3 CDF Run II Preliminary, =5.5 fb 3 CDF Run II Preliminary, =5.5 fb #10 !10 WZ+ZZ 18 Central Shape 70 WW +1 shape Analysis region QCD 16 " W&%$ -1" shape 60 W&µ$ 14

Events / bin W&e$ 50 Single Top 12 Events / 8 GeV tt 40 Z&$$ 10 Z&ll 8 30 6 20 4 10 2 0 0 0.5 1 1.5 2 2.5 3 0 40 60 80 100 120 140 160 "!(MET,closest jet E >5 GeV) T Mjj [GeV]

7/25/11 PANIC11 32 Systematic Uncertainties: Charged Leptons + Jets

CDF Run II Preliminary, L =6.6 fb-1 2 Normalization JES b-tag QG-Tag! Q Z + jets HF Tag Region — 12% +10%,-8.3% — Shape Only LF Tag Region — +14%,-16%± -0.5%,+0.4% +1.0%,-1.9% Shape Only No Tag Region — +16%,-19% -1.0%,+0.9% -0.6%,1.2% Shape Only tt¯ HF Tag Region 6.45% +0.4%,-0.1% +8.9%,-9.8% — — LF Tag Region ±6.45% +0.3%,-0.4% -17%,+16% +11%,-19% — No Tag Region ±6.45% +4.4%,-2.4% -9.5%,+11% -3.8%,6.6% — WW ± HF Tag Region 6% — — — — LF Tag Region ±6% +12%,-9.4% — +20%,-0% — No Tag Region ±6% +32%,-8.4% — -9.6%,-0% — Signal ± HF Tag Region — +4.2%,-4.3% +9.7%,-10% — — LF Tag Region — +5.5%,-4.4% -0.7%,+0.6% +6.3%,-6.6% — No Tag Region — +6.0%,-5.4% -1.2%,+1.4% -6.9%,+7.2% —

Fakes (All Regions) 25% ± + W Z/ZZ l l−jj Search →

7/25/11 PANIC11 33 Systematic Uncertainties: Charged Leptons + Jets

CDF Run II Preliminary, L =6.6 fb-1 Acceptance Uncertainty ! Lepton Energy Scale 0.7% Lepton Energy Resolution ±0.14% Trigger/Lepton Reconstruction Eﬃciency ± 2.2% Jet Resolution ±2.5% ISR/FSR ±1.2% PDF ± 2% Luminosity ± 6% + ± W Z/ZZ l l−jj Search →

7/25/11 PANIC11 34 Systematic Uncertainties: MET + Jets

7/25/11 PANIC11 35 Feldman-Cousins Bands for MET+ Jets

7/25/11 PANIC11 36 Feldman-Cousins Bands for Charged Leptons + Jets

Feldman-Cousins Bands for Limit Calculation

SM 4 -1 ! CDF Run II Preliminary, "L = 6.6 fb /

! Measured Result 68% Coverage Bands 3 95% Coverage Bands

0 0 0.5 1 1.5 2 !Measured / !SM

7/25/11 PANIC11 37