Search of New Phenomena at the Tevatron

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Search of New Phenomena at the Tevatron

• Carlos Sánchez
• For the DØ and CDF experiments

IFAE - Barcelona
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The FNAL Tevatron

• p-pbar collisions at a C.M energy of 2 TeV
• Two experiments around the ring
• CDF and DØ
• Large amounts of data collected
• Analysis on 200 400 pb-1
• Run 2 goal 4.4 8.5 fb-1
• Energy frontier until the LHC turns on

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CDF and DØ

• Both detectors well understood and highly
  efficient
• Extensive calorimeter, tracking and muon coverage

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Looking For SUSY

• Introduces many new particles. Multiple
  signatures available.
• Pair produced.
• Decay into SM partners plus MET.
• No knowledge of how EWKSB occurs ? theorists
  choose models.
• Huge parameter space to explore.
• Very small cross sections.

Looking for new physics with the same old tools
jets, leptons, MET,
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SUSY tri- and dilepton Searches

• Classic tri-lepton SUSY signature
• Trilepton signature is one of cleanest SUSY
  signatures
• Chargino-Neutralino production
• Decay to WZ (or sleptons) 2 LSP
• Low SM background
• But also Small x-section
• Leptonic Br are enhanced if slepton masses are
  close to gaugino masses.
• 2 like-sign leptons signatures available

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Very clean signature
6 analyses -2l(le,m,t)isolated track or
m?m? - MET and topological cuts (Mll,Df, MT)
Selection Bkgnd expected OBSERVED
eel 0.210.12 0
eml 0.310.13 0
mml 1.750.57 2
mm 0.640.38 1
etl 0.580.14 0
mtl 0.360.13 1
SUM 3.850.75 4
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Chargino Neutralino Limits

• mSUGRA M(X) M(X02) 2M(X01)
• 3l-max
• M(slepton) M(X02)
• No slepton mixing
• M(X1) gt 116 GeV
• Heavy squarks
• M(X) M(X02) ? 3M(q)
• M(X1) gt 128 GeV
• Large m0
• M(slepton) gtgt (X02, X)
• No sensitivity

Testing above LEP limit for mSUGRA
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(Work in progress)

• Chargino-neutralino in ee? channel

SELECTION -2 electrons ? (? e,m ) h lt
1 - large MET gt15 GeV/c2 - 15ltMlllt76, gt106
GeV/c2 - Dflt 160 - Njets(20 GeV) lt2
Process
mSugra ee? 0.5
Bkgnd Expected 0.160.07
OBSERVED 0
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Gluino and Squark Search (mSUGRA)
Extended mSUGRA LEP limits
Jets MET

• 4j(gg) M0 500 GeV ? M(g) 233 GeV
• 3j(gq) M(g) M(q) ? M(q) gt 333 GeV
• 2j(qq) M0 25 GeV ? M(q) gt 318 GeV

jets(PT (GeV)) ?Ptjet (GeV) MET (GeV) Bkg. Expected OBS
2 jets(60,50) 250 175 12.85.4 12
3 jets(60,40,25) 325 100 6.13.1 5
4 jets(60,40,30,25) 175 75 9.30.5 10
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Search for Gluinos and Squarks

• 254 pb-1 of data
• Trigger 2 jets MET gt 35 GeV
• 3 jets (125, 75, 25 GeV)
• MET gt 165 GeV, HT gt 350 GeV

• Expect 4.2 ? 1.1 bkgnd events.
• Expect 2.6 4.8 SUSY events.

Observed 3 events in data
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Sbottom Search
ntag Bkgnd Obs.
1 16.4 3.7 21
gt2 2.6 0.7 4
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Stop Search
Expected Observed
Pre-tag 105 12 119
Tag (silicon) 8.3 2.3 11
Selection 2 jets MET lepton veto
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Chargino-Neutralino in gg MET ( )

• 2 photons ET gt 20(13) GeV
• MET gt 40(45) GeV

GMSB G is LSP, stable
Bkgnd Expect Obs Limit mc
D0 3.70.6 2 195 GeV
CDF 0.30.1 0 167 GeV
CDF and D0 combined result m(c)gt209 GeV/c2
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Rp-Violation Searches
Production

• Have assumed Rp conservation
• No proton decay?
• No flavor-violating decays ?
• LSP is stable good dark matter candidate ?
• What if Rp is not conserved?
• Global symmetries are theoretically shaky
• Introduce new terms in MSSM
• Can produce single sparticles
• No stable LSP no dark matter candidate, no
  missing energy.

and decay
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Rp-Violating Sleptons

• Resonant production
• 1.10.4 (Expected) 2 (Observed)

• Decay only

EXP OBS neutralino chargino
0.61.9 0.50.4 1.01.4 2 0 0 84 (GeV) 95 66 165 (GeV) 181 118
µµl eel eet
All improve the Run I results
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Stop in Rp-Violating SUSY(I)

• Assume
• BR(t1?bt) 100
• Search for

selection 1? (?e,m) 1t ? 2 jets
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Stop in Rp-Violating SUSY(II)
Limit Stop gt 129 GeV (same signature as 3rd gen.
LQ)
et mt SUM
Expect. BG 2.60.6 2.20.5 4.80.7
Observed 2 3 5
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Search in High Mass Dileptons

• Relatively clean channel
• Z0 peak as a calibration point
• Many models to explore
• Z, TC, RS graviton, LED
• compositeness, etc

?Ldt 200 pb-1
ee
ZSM 600 GeV
ee
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Z Limits
CDF tt
DØ µµ
SM Couplings ee mm eemm tt
CDF 750 735 815 394
DØ 780 680 E6
ZI Z? Z? Z? CDF
610 670 690 715 (eemm) DØ
575 640 650 680 (ee)
DØ ee
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W Search in en Channel

• W additional charged heavy vector boson
• Appears in theories based on extension of the
  gauge group
• Left-right symmetric models SU(2)R ? WR
• Assume the neutrino from W decay is light and
  stable.
• signature

MC only
High PT lepton high MET
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W Search (cont.)
MT Distribution of Data
highest MT event MT 524 GeV/c2
sB(W ? enu) limit 50 100 fb for M(W) gt
500 GeV/c2 at 95 CL.
Limit M(WSM )gt 842 GeV/c2
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Leptoquarks
GUTS, Technicolor, Compositeness, RPV-SUSY assume
an additional symmetry between leptons and
quarks.
Carry both lepton (L) and baryon (B)
numbers Couple to quark and lepton of the same
generation.
At the Tevatron they are pair produced.
Selection high PT isolated lepton(s) and/or MET
2 jets.
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1st, 2nd, and 3rd Generation LQ
channels mmjj, enjj, nnjj
channels eejj, enjj, (nnjj)
D0 Run I II, MLQ gt 256 GeV/c2 CDF Run II, MLQ
gt 235 GeV/c2
D0 Run I, MLQ gt 200 GeV/c2 CDF Run II, MLQ gt
224 GeV/c2
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Extra Dimensions (ED)
exchange

• Alternatives to SUSY for solving the hierarchy
  problem (MEW ltlt MPlanck ???)
• Several different models
• Large ED
• TeV-1 ED
• Warped ED

Arkani-Hamed, Dimopoulos, Dvali Phys Lett B429
(98)
Dienes, Dudas, Gherghetta Nucl Phys B537 (99)
Randall, Sundrum Phys Rev Lett 83 (99)
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Extra Dimensions (ED)
LED with mm
LED with ee gg
Signal prediction
QCD
Stadard Model
No deviation from SM predictions
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Randall-Sundrum Graviton (ee mm gg)
Dileptons have largest acceptance at low mass
while ?? has largest acceptance at high
mass BR(G???) 2 BR(G?ee)
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Conclusions

• Delivered data at the Tevatron over 1 fb-1
• CDF and DØ running efficiently
• Interesting regions of parameter space (for many
  models) are now in reach
• Testing beyond LEP limits
• Improving Run I results
• Many new exciting results from Tevatron
  experiments and more coming soon!

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Backup slides
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CDF Luminosity
Over 1 fb-1 delivered
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Technicolor
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Mass Bump Search Strategies

• Perform general searches comparing data to
  expectation
• Determine spin dependent acceptance and ?.BR
• Interpret the results according to many new
  models!
• Spin-0 RPV sneutrinos
• Spin-1 ZSM, E6 Z, Little Higgs Z, TC (rT,
  wT)
• Spin-2 RS graviton

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Spin Dependence Acceptance

• Angular distribution and therefore
  acceptance of decay product depends on the spin
  of the decaying particle.

central h lt 1.1 forward 1.1 lt h lt
3.6
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sB Limits (ee and mm channels combined)

• sBr limit 25 fb for all spins for the high
  mass region (MLL gt 600 GeV)