new physics searches at the tevatron · the classic searches e+e-: probe z’, rs graviton… 0 100...

New Physics New Physics SearchesSearches at the at the TevatronTevatronAmitabh Lath

Rutgers University/CDFFor the CDF and D0 Collaborations

ICHEP 2004Beijing

CDF D0

TevatronTevatron:: The Energy FrontierThe Energy Frontier1.96 TeV CM Energy

500 pb-1 to tape NOW4 fb-1 to tape by FY 2009.

(8 fb-1 possible?)

• When will new physics show up?• What will it look like? • Will our triggers and analyses be sensitive to it?

We need to think beyond established theories

Main Injector& Recycler

Tevatron

Chicago!↓

⎯p source

Booster

⎯p

p

p ⎯p1.96 TeV

CDFDØ

New Physics:New Physics: Beyond Higgs, SUSYBeyond Higgs, SUSY

Use familiar objects: e, µ, τ, γ, jet, ET

Massive Objects:Z’/W’, Gravitons (leptons, photons)

Leptoquarks (leptons, ET , jets)

Extra dimensions (leptons, jets, ET)

Compositeness:Excited Fermions (leptons, photons)

Technicolor (leptons)

Truly Exotic ObjectsCharged Massive Particles (CHAMPS)Magnetic Monopoles

The Classic SearchesThe Classic Searchese+e-: Probe Z’, RS Graviton…

0 100 200 300 400 500 600 700 800 900-410

-310

-210

-110

1

10

210

310

410

/ ndf 2χ 62.63 / 53Prob 0.1716p0 0.71± 24.03 p1 0.00005± 0.01187

/ ndf 2χ 62.63 / 53Prob 0.1716p0 0.71± 24.03 p1 0.00005± 0.01187

0 100 200 300 400 500 600 700 800 900-410

-310

-210

-110

1

10

210

310

410

/ ndf 2χ 62.63 / 53Prob 0.1716p0 0.71± 24.03 p1 0.00005± 0.01187

DØ Run II PreliminarydiEM Mass Spectrum

)2

Dielectron Mass (GeV/c

100 200 300 400 500

)2E

vent

s / 5

(G

eV/c

10-1

1

10

102

103

104

Data

Drell - Yan

QCD Background, WW, WZ, ttττ

)2

Dielectron Mass (GeV/c

100 200 300 400 500

)2E

vent

s / 5

(G

eV/c

10-1

1

10

102

103

104

)-1

CDF Run II Preliminary (200 pb

Hypothetical Z’

Note: agreement over 2 ordersof magnitude in mee.

Large Extra dimensions

D0 Run II 200 pb-1

D0

The Classic SearchesThe Classic Searches continuedcontinuedµ+µ− : Probe Z’, RS Graviton…

100 pb-1

Dimuon Invariant Mass (GeV)0 200 400 600 800

Eve

nts

/ 24

GeV-210

-110

1

10

210

310

410

DØ Run II Preliminary

DataSM Monte Carlo

D0

D0 250 pb-1

)2

Dimuon Mass (GeV/c100 200 300 400 500 600 700 800

2E

ven

ts /

5 G

eV/c

10-2

10-1

1

10

102

103

DataAll

µµDY Z->QCD+cosmics

t, WW, WZ, tττDY Z->

)-1

CDF RUN II Preliminary (200 pb

e uses EM calorimeter, resolution better at harder e.µ uses tracker, resolution better at softer µ.

e,µ complimentary:

Typical High Mass events. Typical High Mass events. CLEAN!CLEAN!

eta

-4.7 -3

-2 -1

0 1

2 3

4.7

phi180

0

360

ET(GeV)

185

Bins: 400Mean: 1.03Rms: 11.2Min: 0.00516Max: 183

mE_t: 15.7phi_t: 351 deg

Run 175826 Event 15382214 Wed Jan 28 19:15:22 2004

CDFD0

Historically ee, (µµ) searches have paid off handsomely at hadron machines.

Insensitive to QCD remnants.

DileptonDilepton CrossCross--Section Limits: Section Limits: eeee

Mass (GeV)200 300 400 500 600 700 800

) (pb

)γγ

ee

&

→ x

BR

(G

σ10

-4

10-3

10-2

10-1

1

10

102

95% CL upper bound = 0.01Plk / M = 0.02Plk / M = 0.05Plk / M = 0.10Plk / M


)2

Z’ mass (GeV/c

200 400 600 800

ee)

(pb)

→Br

(Z’

⋅σ

10-3

10-2

10-1

1

10

102

)I570 GeV (Z

)χ610 GeV (Z

625 GeV)ψ (Z

650 GeV )η (Z

750 GeV(Z’ SM coupling)

ll) limit (95% C.L.)→Br(Z’⋅σ1.3× ll) LO→Br(Z’⋅σ

)-1


)2

Z’ mass (GeV/c

200 400 600 800

ee)

(pb)

→Br

(Z’

⋅σ

10-3

10-2

10-1

1

10

102

D0:Z’ ee Limit 780 GeV/c2

CDF :Z’ ee Limit 750 GeV/c2

D0 200 pb-1

LIMIT

S

~50 fb

D0

DileptonDilepton CrossCross--Section Limits:Section Limits: µµµµ

)2

Mass (GeV/ cHZ350 400 450 500 550 600 650 700 750 800

ll)

(pb

)→

H.B

R(Z

σ

10-4

10-3

10-2

10-1

1

10

102

)2

Mass (GeV/ cHZ350 400 450 500 550 600 650 700 750 800

ll)

(pb

)→

H.B

R(Z

σ

10-4

10-3

10-2

10-1

1

10

102 ll) limit (95% C.L.)→.BR(Z'σ

1.3)× ll) (LO→H.BR(Zσ

)-1


= 0.5θcot

= 0.7θcot

= 1.0θcot

CDF :Z’ µµ Little Higgs(cotθ=0.7) 720 GeV/c2

D0 250 pb-1

D0 :Z’ µµ (SM) > 680 GeV/c2LIM

ITS

~60 fb

Dimuon Invariant Mass (GeV)200 300 400 500 600 700 800 900

) (p

b)

µµ →

BR

(Z’

× σ

-210

-110

1

10

1.3)×SM Like Z’ Theoretical (LO Errors on Theoretical Cross Sectionσ 1 ±

95% CL Experimental Limits


Technicolor:Technicolor:

)2

mass (GeV/cTω,Tρ200 300 400 500 600

ee)

(pb

)→

Br(

Z’

⋅σ

10-3

10-2

10-1

1

10 ee) limit (95% C.L.)→Br(Z’⋅σ

1.3× ee) LO→Tω,TρBr(⋅σ

)-1


Tω=MTρM

- 100 GeVTρ=M

TπM

= 400 GeVTM

= 300 GeVTM

= 200 GeVTM

)2

mass (GeV/cTω,Tρ200 300 400 500 600

ee)

(pb

)→

Br(

Z’

⋅σ

10-3

10-2

10-1

1

10

)2

Mass (GeV/ cTρ, Tω200 250 300 350 400 450 500 550 600

) (p

b)

µµ →

.BR

(Z'

σ

10-4

10-3

10-2

10-1

1

10

)2

Mass (GeV/ cTρ, Tω200 250 300 350 400 450 500 550 600

) (p

b)

µµ →

.BR

(Z'

σ

10-4

10-3

10-2

10-1

1

10 ) limit (95% C.L.)µµ →.BR(Z'σ1.3)×) (LOµµ →Tρ, Tω.BR(σ

)-1


=400 GeVTM

=300 GeVTM

=200 GeVTM

Almost there! Need another order of magnitude

Another promising channelAnother promising channel: : DiphotonDiphotonEvent : 2045232 Run : 165271

Diphoton Mass = 405 GeVPhoton Et = 172, 175 GeV

γ an e without a track.

LIMITS

~70 fb

Combined LimitsCombined Limits: : Graviton, LEDGraviton, LED

•Pairs of hard, isolated leptons and photons are powerful tools to hunt new physics.

•The SM backgroundsare small and well understood.

•The results are σ*BR, which can be interpreted in a variety of ways by different models (some of which haven’t been published yet!)

η = F/Ms4

D0 Extra dimensions

η limit:0.24 TeV-1

MPL>1.43 TeV (GRW) World’s best limit on MPL Mass (GeV)200 300 400 500 600 700 800

Pl

k / M

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.1

Mass (GeV)200 300 400 500 600 700 800

Pl

k / M

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.1

Randall-Sundrum gravitons

95% CL excluded domain

decay modesγγee &

DØ Run II PreliminaryD0

Adding Adding EETT : : WW’’ SearchSearch

Electron + ETNeutrinos show up as MET

Many sources of ET tails:MuonsCracks in detectorEnergy calib.

Plot shows we have good understanding of ET.)2 (GeV/cTM

0 100 200 300 400 500 600

2E

vent

s pe

r 4

GeV

/c

-210

-110

1

10

210

310

410data

sum of backgrounds

ν e →w

hadronic jets

other backgrounds

)-1


W’ limit plotwork in progress.

e+e+γγ: Compositeness : Compositeness (Excited electrons)(Excited electrons)

q

q e*

e

γ

e

q

q

Z

e*

e

γ

e

contact

Gauge mediated

Electron + γ

3 events seen

meγ

Limits on excited electronsLimits on excited electrons

GaugeLIM

ITS

~70 fb

Electrons+JetsElectrons+Jets: : LeptoquarksLeptoquarks

Mass (GeV)0 50 100 150 200 250 300 350 400 450 500

Nev

ents

/5G

eV

10-1

1

10

102 DØ Run II Preliminary

DataTotal BkgZ/DY Bkg

QCD Bkg

(GeV)TS0 100 200 300 400 500 600 700

Neve

nts/

25G

eV

1

10

Data


Total BkgZ/DY BkgQCD BkgTop Bkg

LQ (240GeV)

Two energetic electrons.Two jets 1st gen. LQ

Scalar Energy sum, eejj

D0

D0

Electrons+JetsElectrons+Jets: : LeptoquarksLeptoquarks

β =1 •Limit ~ 100 fb•More challenging at lower mass.

• QCD bg requires hard cuts that affect limit at low mass.

• Jets harder to study than e, γ• Jet multiplicity hard to simulate.• Jet quark, g correspondence hard to disentangle• Jet energy resolution not nearly that of e, γ.

Two energetic electrons.Two jets

Scalar Leptoquark Mass (GeV)180 200 220 240 260 280

BR

(pb)

×C

ross

Sec

tion

10-2

10-1

1


> 238 GeVLQ

DØ Run II, M

NLO Theory

238 GeV/c2

D0

Electron+Jets+EElectron+Jets+ETT: : LeptoquarksLeptoquarks

•One energetic electron.• ET

• Two jetsβ is BR(LQ eq) =0.5

197 GeV/c2

Limit

~ 100 fb

D0

Jets + EJets + ETT: : LeptoquarkLeptoquark

(GeV)TMissing E50 100 150 200 250 300

Eve

nts

/ 10

GeV

0

10

20

30

40

50

Data

QCD prediction

predictiont+ SM EWK / t

)2

LQ (m = 125 GeV / c

CDF Run II Preliminary

-1 L dt = 191 pb∫

(GeV)TMissing E50 100 150 200 250 300

Eve

nts

/ 10

GeV

0

10

20

30

40

50

)2

Leptoquark Mass (GeV/c80 100 120 140

(pb)

2 )β x

(1-

σ10

102

CDF Upper Limit, 95% CL

Theoretical cross section (PRL 79, 1997)

CTEQ5M, Q=m(LQ)

CTEQ5M, Q=0.5m(LQ), 2m(LQ)

)-1CDF Run II Preliminary (191 pb

278 - 117 GeV/cNo electrons in final stateLeptoquark goes to ν, jet.

Challenging at low mass.

Important for squark/gluino searches

LeptoquarksLeptoquarks (1(1stst Gen. Limits)Gen. Limits)

Scalar Leptoquark Mass (GeV)140 160 180 200 220 240

eq

)→

= B

ran

chin

g R

atio

(L

Q

β

0

0.2

0.4

0.6

0.8

1DØ Run II Preliminary

DØ Run II

Combin

ed L

imit

ee + 2 jets

+ 2 jetsνe

D0 200 pb-1D0

Now with Now with µµ:: LQ 2LQ 2ndnd GenerationGeneration

)2

Leptoquark Mass (GeV/c160 180 200 220 240 260 280 300 320

(p

b)

2β ×

σ

10-2

10-1

1

)-1


Theoretical Cross Sections, Phys Rev Lett 79, 341, ’97

LQCTEQ4M, Q = M

LQCTEQ4M, Q = 0.5, 2 M

CDF upper limit, 95% CL

2 events observed

GenerationndSearch for 2

= 1βScalar Leptoquarks,

2 > 241 GeV/cLQM

) [GeV]2(jT) + E1(jTE0 50 100 150 200 250 300 350 400 450 500

) [G

eV]

2µ(T

) +

P1µ(

TP

0

50

100

150

200

250

300

350

400

450

500-1Int. Lum = 2.5 fb

LQ m=220 MC

DY,Top MC

Kinematic sig/bkg discrimination

Two muons,Two jets.

Limit

~ 70 fb

Jets+METJets+MET:Large:Large Extra DimensionsExtra Dimensions

missing ET0 50 100 150 200 250 300 350 400 450 500

Eve

nts

/ 10

1

10

102

103

104


DataMCSignal

second jet pT0 50 100 150 200 250 300 350 400 450 500

Eve

nts

/ 10

0

10

20

30

40

50

60

70DØ Run II Preliminary

DataMCSignal

Nd4 5 6 7

Md

(G

eV)

500

600

700

800

900

1000 DØ prelim.DØ Run ICDF Run IL3

No k factor

Most stringent

Number of Dimensions

Need to understand calorimetry, tracking, acceptance in excruciating detail.

QC

D

D0

D0

D0D0

A special sort of jetA special sort of jet: : ττ hadronshadronssignalisolationseed track

not associatedwith tau candidate

θsig

isoθ

Track Multiplicity0 1 2 3 4 5 6 7

Eve

nts

0

20

40

60

ττ→ZOther Backgrounds

Control Sample, Tau Signatureττ-1CDF Run 2 Preliminary 195 pb

See Weiming Yao’s talk for more on taus

100 200 300 400 500 600

1

10

CDF Run 2 195 pb-1

PreliminaryZ'→ττ

95% CLupper limit

mZ' (GeV)

σ•B

(Z'→

ττ)

(p

b)

sequential Z'cross section

LIMITS

~1000 fb

Truly Exotic:Truly Exotic: CHAMPSCHAMPSCHAMPS are slow moving

Large Ionization lossLong time of flight

Highly penetratingWill look like a muon

Entries 6266

Mean -0.02381

RMS 0.3529

(ns) TOF∆-5 -4 -3 -2 -1 0 1 2 3 4 5

Num

ber o

f tra

cks

/ 0.1

ns

1

10

102

103

Entries 6266

Mean -0.02381

RMS 0.3529

Pt > 40 GeV/c

CDF Run 2 Preliminary

-1 = 53 pbL dt ∫

misolated-stop > 108 GeV/c2

LIMITS

~10,000 fb

CHA

MP

Truly Exotic: Truly Exotic: MonopoleMonopole

B=1.4 T

COT

Solenoid

TOF

Beam

z

TOF

COT

Monopole

Segment

•Bends in the wrong plane ( high pt)•Large ionization in scint (>500 Mips!)•Large dE/dx in drift chamber

Monopole Mass [GeV]200 400 600 800

Cro

ss S

ectio

n [p

b]

10-3

10-2

10-1

1

10

102

103

Drell Yan cross section

sensitivity

CDF Run II Preliminary

95% CL Limit

mmonopole > 350 GeV/c2

LIMIT

S

~300 fb

TOF t

rigger d

esigne

d

specif

ically fo

r mono

pole

search

SummarySummaryTevatron luminosity is ramping up.

4 fb-1 promised by 2009. Exciting physics possible.Translating detector understanding to physics.

Objects like e, µ, γ, τ, ET, jets, (b) are now reconstructed w/ excellent efficiency, purity. We use these to search for V’, Technicolor, LQ, excited fermions, extra dim...Going to get even better: More luminosity, better understanding.Now, limits ~50 - 100 fb (leptons, photons). Soon, ~10 fb!

We think outside the box.Hunt for new objects like CHAMPS, monopoles…Could use help from theorists here.

We hope to see new physics soon.We are sick and tired of making exclusion plots!

Backup slides

TevatronTevatron Promises High LuminosityPromises High Luminosity……

Aug04: ~0.7fb-1

delivered: > design

12 pb-1 / week currently: above “design”

Start of Fiscal YearOct 03

4 fb-1 line : 2009? Earlier?

Slam dunk!

But can they deliver?But can they deliver?

Run 1

Last 30weeks

Recent news is encouraging!

new physics searches at the tevatron · the classic searches e+e-: probe z’, rs graviton… 0 100...

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