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Higgs Searches Higgs Searches at the Tevatronat the TevatronHiggs Searches Higgs Searches at the Tevatronat the Tevatron

Chris TullyPrinceton

On behalf of the CDF/D0 Collaborations

SUSY 2005IPPP Durham, England, July 18-25, 2005

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Low Energy SupersymmetryLow Energy Supersymmetry

The Higgs Sector is vacuous without it…The Higgs Sector is vacuous without it…

Stability of the Electroweak scale is as fundamental and as deserving a resolution as Classical E&M arguments were to the instability of atomic states posed over a 100 years ago.

We can only hope the answer will be equally far reaching…

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Preferences from MPreferences from MWW and m and mtoptop

Error on mError on mtoptop no no

longer dominateslonger dominates

W self-energy W self-energy may be decisive may be decisive once Monce MWW

improvesimproves

Mtop = 172.7 ± 2.9 GeVNew CDF/D0 Mass

Combination

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New Top Mass CombinationNew Top Mass Combination

This includes new This includes new preliminary preliminary measurements measurements (based on 320 pb(based on 320 pb-1-1) ) from CDF/D0 which from CDF/D0 which simultaneously fit simultaneously fit the jet energy scale the jet energy scale with the hadronic W with the hadronic W mass constraintmass constraint

The correlated The correlated systematical error is systematical error is of order ~1.7 GeVof order ~1.7 GeV

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SUSY GuidanceSUSY Guidance

• Lightest Higgs mass compatible with high tan region for wide range of stop mixing

Heinemeyer, Weigleinqd,ℓ–

qd,ℓ+

cos

sin

cos

cos

cos

sin

h:

H:

A:Use tanβ enhancement!

LEPPreliminary

down-type

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Large b-ProductionLarge b-Production But how well known…But how well known…

Use Leptonically Decaying Z’s as a probe!

B-hadronLifetime tag

Z+b

PRL 94, 161801 (2005)

152-184 pb-1

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MSSM Higgs b(b)MSSM Higgs b(b) Search Search b(b)b(b) → b(b)bb → b(b)bb =h/A or H/A=h/A or H/A

At least 3 b-tagged jetsAt least 3 b-tagged jets Data-derived background shapeData-derived background shape

Leading

Submitted to PRL

260 pb-1

at 95% Excl.

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b(b)b(b) Limits: tan Limits: tan22ββ EnhancementEnhancement

22

2

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1

tan2

bb

SMSUSYBR

Enhancement depends on loop corrections (Δb) and SUSY parameters:

260 pb-1

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b(b)b(b) Projections Projections

CDF+

1 fb-1

8 fb-14 fb-12 fb-1

b

t

m

mtan

Tevatron will probe below

!

Projection based on existing analysis:Doesn’t include proposed b-tag improvements

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Higgs Decays to Higgs Decays to -leptons-leptons --

Identification Identification Methods Methods (CDF)(CDF)

BeforeOS req.

Method yields a rich sample of taus with the expected visible masses and track multiplicities from Z→

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h/H/Ah/H/A→→ SearchSearch Visible Mass is the final Visible Mass is the final

search variable:search variable:

tan=30

H

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MSSM HiggsMSSM Higgs→→ Search Search tantan Exclusion Limits: Exclusion Limits:b(b)

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HiggsHiggs→→ Projections Projections

HiggsHiggs→→ and and b(b)b(b) will reach will reach similar similar sensitivities at sensitivities at the same timethe same time

Opens up exciting prospects for learning more about SUSY as yb and y see different loop-corrections

Assumes several analysisimprovements

CDF+D0

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Charged Higgs from top quark Charged Higgs from top quark decaydecay

Predicted to substantially modify top Predicted to substantially modify top quark Branching Ratios at high and low quark Branching Ratios at high and low tantan

Additional sensitivity in lepton + Additional sensitivity in lepton + channel channel

mH+ =

100 GeVmH

+ = 140 GeV

cs t*b

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HH++ tan tan ExclusionExclusion

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Br(tBr(t→→HH++b) Exclusion for b) Exclusion for Br(HBr(H++→→)=1)=1 Range of Exclusions Br<0.4 to Br<0.7 Range of Exclusions Br<0.4 to Br<0.7

depending on MSSM parametersdepending on MSSM parameters

H+→cs Search in progress…

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Lightest Higgs BosonLightest Higgs Boson

• Lightest Higgs boson is SM-like for large MA

• Given the difficulty of detecting the h→bb decay at the LHC, the Tevatron provides a potentially essential probe of this low mass channel

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2tan2tanZA

ZA

MM

MM

HHA MMM (decoupling limit)

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Low Mass Higgs SearchLow Mass Higgs Search Maximum sensitivity requires a Maximum sensitivity requires a

combination of CDF/D0 search combination of CDF/D0 search channels:channels: WHWH→ℓ→ℓbb, ZHbb, ZH→→bb & bb & ℓℓbb, WHℓℓbb, WH→WWW→WWW**, ,

H→WWH→WW

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ℓℓbb Search (CDF)bb Search (CDF)

319 pb-1

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eebb Search (DØ)bb Search (DØ) bb in Progress…bb in Progress… Expect 0.14 ± 0.03 WH

4.29 ± 1.03 Wbb 5.73 ± 1.45 tt+otherTotal 10.2 ± 2.4 eventsObserve 13

Tagged Sample≥1 b-tag

Double-Tagged Sample

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Missing Energy Channel Missing Energy Channel (CDF)(CDF) Two Control Regions:Two Control Regions:

No Leptons + No Leptons + (E(ETT, 2, 2ndnd Jet)<0.4 (QCD H.F.) Jet)<0.4 (QCD H.F.)

Min. 1 Lepton + Min. 1 Lepton + (E(ETT, 2, 2ndnd Jet)>0.4 (Top, EWK, Jet)>0.4 (Top, EWK,

QCD)QCD)Control Region 1 Missing ET

b-jet

b-jet

y

x

• Large ET

• Two jets (one b-tagged)

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Missing Energy Missing Energy Event (CDF)Event (CDF)

Second Jet ET = 54.7 GeV 

Leading Jet ET = 100.3 GeV

Double tagged eventDi-jet invariant mass = 82 GeV

Missing ET

144.8 GeV

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Missing Energy Channel Missing Energy Channel (CDF)(CDF)

Selection cut ZH 120 (288.9 pb-1)

Di-jet mass cut (100,140)

0.1260.016

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Missing Energy Channel (DMissing Energy Channel (DØØ)) Cross-efficiency Cross-efficiency

importantimportant WHWH→→ℓℓbb (lost ℓ)bb (lost ℓ) ZHZH→→bbbb

3x Larger WZ/ZZ Signal3x Larger WZ/ZZ Signal Similar dijet bb mass peakSimilar dijet bb mass peak

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WHWH→→WWWWWW** (CDF) (CDF)

Vector pT Sum

2nd L

epto

n p

T

Fake Lepton Region

“One Leg”PhotonConv.

0.03 SM Signal ExpectedmH=160 GeV

No EventSeen

Same-Sign Dilepton Search

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WHWH→WWW→WWW** (DØ) (DØ) WWWWWW**→→ℓℓ± ± ℓℓ± ± + X+ X

Same-Sign DileptonsSame-Sign Dileptons

Important bridge Important bridge across 130-160 across 130-160 GeV “Gap” from GeV “Gap” from HH→→bb and inclusive bb and inclusive HH→WW→WW

Background from Background from WZ→WZ→ℓℓℓℓℓℓ

363-384 pb-1CDF 194 pb-1

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HH→→WW (DWW (DØ)Ø)

Leptons from Higgs tend to point in same direction

Apply ℓℓ< 2

ℓℓ< 2

WW cross section measured

PRL 94, 151801 (2005)

WW =13.8 (st.) (sy.) ± 0.9 pb+4.3 +1.2–3.8 –0.9

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Overview of CDF/DOverview of CDF/DØ SM Higgs Ø SM Higgs SearchesSearches

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Prospects for SM Higgs Prospects for SM Higgs SearchSearch Current analyses sensitivities are Current analyses sensitivities are lower than used for projections, but lower than used for projections, but differences appear to be recoverabledifferences appear to be recoverable

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SummarySummary MSSM tanMSSM tan enhancement searches enhancement searches

b(b)b(b) & Higgs & Higgs→→already sensitive to tanalready sensitive to tan~50-~50-6060

Plans to add b(b)Plans to add b(b)→→b(b)b(b) tt→→HH++b, Hb, H++→→ results (Plans to add H results (Plans to add H++→cs→cs))

SM Higgs searchesSM Higgs searches Full complement of search channels with first Full complement of search channels with first

resultsresults Will be important to benchmark search sensitivity Will be important to benchmark search sensitivity

with WZ diboson production with Zwith WZ diboson production with Z→→bbbb ~1 fb~1 fb-1-1 to analyze by Fall to analyze by FallCombine, combine, combine…

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Backup Plots & Backup Plots & TablesTables

Backup Plots & Backup Plots & TablesTables

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Tevatron PerformanceTevatron Performance

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SM Higgs Production SM Higgs Production ProcessesProcesses

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ZZ→→bb (CDF)bb (CDF)

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ℓℓbb Search (CDF)bb Search (CDF)

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HH→→WW (DWW (DØ)Ø)

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Improvements to b-taggingImprovements to b-tagging

Operating

Point

~ Fake Rate ~ b Efficiency

Tight 0.25 % 44 %

Medium 0.5 % 52 %

Loose 1.0 % 57 %

Loose2 2.0 % 64 %

Loose3 3.0 % 68 %

Loose4 4.0 % 70 %

Analysis depends on strongly on b-tagAnalysis depends on strongly on b-tag Neural Net b-taggingNeural Net b-tagging

DØ

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ZZ→→ as a benchmark as a benchmark DDØØ Neural Network Neural Network

-Selection-Selection Variables:Variables:

Shower ProfileShower Profile Calorimeter IsolationCalorimeter Isolation Track IsolationTrack Isolation Charged Momentum Charged Momentum

FracFrac Opening AngleOpening Angle Etc.Etc.

3 Types:3 Types: -like-like -like-like Multi-prongMulti-prong

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Missing Energy Channel (DMissing Energy Channel (DØ)Ø)• Trigger on event w/ large ET & acoplanar jets

• Instrumental ET backgrounds (Data-driven estimation)

– Asymmetries computed: Asym(ET,HT) and Asym( pTtrk

,pT2trk)

DataData in

signal region

Signal

Sidebands

ExponentialSignal

Instr. Backgroundfrom Sidebands(Data)

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Missing Energy Channel (DMissing Energy Channel (DØ)Ø)No b-tag Single b-tag Double b-tag

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HH→→WW (CDF)WW (CDF)Cluster mass:

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ℓℓℓℓ MpM TC

=184 pb-1