SUSY Searches at the Tevatron

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SUSY Searches at the Tevatron

• Alexei Safonov
• University of California, Davis
• For CDF and D0 Collaborations

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Tevatron Status

• Upgrades for Run II
• Main Injector (150 GeV proton storage ring
  replaces Main Ring.
• Shorter interbunch spacing (396 ns)
• Beam Energy CM 1.96 TeV
• Instantaneous Luminosity
• 4.1 x 1031 cm-2s-1 peak luminosity
• Expected Goals
• 250 pb-1 by Summer 2003
• 2000 pb-1 for Run IIa

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Status of the Detectors
CDF Integrated Luminosity
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Many Faces of SUSY

• SUSY has many faces
• MSSM (LSP is , Signature is generally
  leptons, jets and MET)
• mSUGRA (LSP is or , Signature is generally
  leptons, jets and MET)
• 3rd Generation/High tanb (mixing ? light
  stop/stau, many taus in final state)
• RPV (LSP varies, Signature is more leptons, less
  MET. We concentrate on RPV couplings that lead to
  lepton number violation)
• GMSB (LSP is gravitino, leptons or photons and
  MET)
• AMSB ( , near mass-degenerate, more
  difficult experimentally and requires special
  treatment)

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Run II and SUSY Searches

• In many cases, setting competitive limits
  requires
• large luminosity
• going to the low end in energies (cascade decays
  and massive escaping )
• sharp cuts between signal and background
• Thorough understanding of backgrounds and
  calibrated detector response at low transverse
  momentum
• Presented Run II results mostly refer to
  scenarios at higher end of energy spectra.
• Updated Run I results utilize improved knowledge
  of those difficult lower energies.

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At Higher End of Energies Z

• Typical high energy end study
• ETgt20 GeV
• PTgt13 GeV
• Calorimeter Iso/ETlt0.1(0.2)
• Limits on Z and Graviton extracted.
• Can be used to set SUSY limits.

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Low tanb SUSY trileptons

• mSUGRA
• Cuts
• 2e PTgt15(10),
• 10ltMeelt70
• MT(e,MET)gt15
• Iso Track PTgt5,hlt3
• METgt15
• No events observed (0.0/-1.4 expected)

• D0, Run II, 42 pb-1

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Search for MSSM Stop

• Heavy top, mixing -gt stop can be light

• Updated CDF Search, Run I 106 pb-1
• Lepton PTgt10 GeV
• Second Lepton PTgt10 GeV
• METgt30 GeV
• BG DY, bb,cc, fakes.

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SUSY at higher tanb

• Consider standard trilepton search

• Large tanb is theoretically motivated
• At tanb gt8 final state leptons are dominated by
  ts.
• Tau channels are very important in Run II!

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Run II Advances on Tau Front

• Taus were traditionally more difficult for both
  experiments. Clear need for a significant
  improvement.
• CDF LeptonTrack (LT) Triggers
• Lepton PTgt8 GeV (electron or CMUP/CMX muon)
• Tau-style isolated 5 GeV track
• Targets multilepton final states including taus.
• Installed and commissioned in January 2002.

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CDF W/Z-gttau tau

• Hadronic Tau track multiplicity
• Fit of the data to the MC signal predictions plus
  expected shape of the jet fake backgrounds
• Mass plot (OS data only)
• Signal normalization as in the mutiplicity plot,
  fit for the fake fraction.

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D0 Z-gttau tau

• Tau Definition
• Calorimeter Cluster R0.4
• RMS(cluster size)lt0.25
• At least 1 track

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Search for R-parity violation

• Test 3rd gen. RPV coupling
• CDF, Run I 106 pb-1
• Final state looks like LQ3 analysis.
• Lepton(e,m)tNjets
• Improvements
• Lower electron cut, PTgt10 GeV
• Track-based th id, include p0 reconstruction

Significantly improves acceptance for Compared to
earlier Run I studies
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Search for R-parity violation

• CDF Run I L106 pb-1

2TeV
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Searches for GMSB

• D0 (Run II, 42 pb-1)
• 2EM Clusters Etgt20 GeV, hlt1.1
• EM clusters point to same vertex
• Jets cone 0.7
• Dq (leading jet, MET) lt 2.6
• No jets in 1lthdetlt1.5

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Searches for GMSB

• D0 Limit set for
• Messenger mass scale Mm2 L
• Equiv. of 55 m-fields N51
• tanb15
• sign(m)gt0

Run II Limit Run I
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Conclusions

• Tevatron operating at worlds highest energy
• Both experiments are commissioned and taking
  physics data.
• First Run II results available in an assortment
  of SUSY models tested (mostly in the high ET
  region).
• Higher CMS energy allows competitive results with
  Run I even at lower luminosities.
• Competitive SUSY results will need more time,
  both in terms of luminosity and in detailed
  understanding of the detector efficiencies and
  backgrounds in the low ET region.
• CDF and D0 carefully including tau leptons to
  searches for new physics now
• More analyses to come soon.