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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
DØ Run II Preliminary
)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
CDF Run II Preliminary (200 pb
)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
CDF Run II Preliminary (200 pb
= 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
DØ Run II Preliminary
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
CDF Run II Preliminary (200 pb
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
CDF Run II Preliminary (200 pb
=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
CDF Run II Preliminary (204 pb
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
DØ Run II Preliminary
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
DØ Run II Preliminary
> 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
CDF Run II Preliminary (198 pb
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
DØ Run II Preliminary
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!