SUSY particles searches with R-parity violation at D

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SUSY particles searches with R-parity violation
at DØ, Tevatron.(?121 coupling)

• Introduction
• Analysis
• Results
• Comparison with other experiments
• Conclusion and prospects

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Final state with ?121 coupling
ii) Decay Rp violated with ?121 coupling ? Decay
of the neutralinos into leptons.
Final state eeee, eeeµ, or eeµµ
iii) Detector not fully efficient ? we search for
eeX, X e or µ
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Data sample and SM background

• DØ Run II DATA from sept 2002 to june 2004
• ? 310 20 pb-1.
• preselection 2 EM objects pT gt 7
  GeV.c-1 or 1 EM 1 µ both pT gt 5 GeV.c-1.
• Standard Model (SM) background all processes
  with ee or eµ final states, generated with
  Pythia, Alpgen.
• Z?ee, Z?µµ, Z?tt between 5 and 1960 GeV,
• WW?l?l?, WZ, ZZ,
• W ? l?
• ttbar ? ll,
• ?(1s)(2s) ? ee, ?(1s)(2s) ? µµ

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Main selection criteria
- at least 3 isolated leptons between them and
from jets, in fiducial zones. - tight
electrons standard cuts on the shape of the
cluster in EM calorimeter, requirement of a track
in the inner tracking system. - tight muons
identified from inner tracking system to last
muon chamber. - Triggers one OR two EM objects,
OR one muon and one EM object.
m0 250 m1/2 195 tanß 5 µ lt 0
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A example of trigger effect

• Selection of 2 tight electrons, triggered by a
  jet trigger (? unbiaised sample), how many do
  also trig an EM or a DIEM trigger ?
• EM trigger ? 100 efficient after 50 GeV, 15 eff
  at 10 GeV.
• DIEM triggers ? 100 efficient after 30 GeV, 50
  eff at 10 GeV
• ? we need both triggers

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Plots to check our understandingof the data
After selection of 2 tight electrons.
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Cuts applied to select ee X

• Cuts to remove background
• Z, WZ, ZZ ,
• ? cut on invariant mass of any ee pair
  Mee ?80,100 GeV.c-2.
• Zjets ? lljets, and a b jet which decays into
  a muon,
• ? cut on isolation of the muon
• ? conversion in ee-,
• ? require hits in inner tracker layers
• We expect transverse missing energy in the signal
• ? cut on MET gt 15 GeV.

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Remaining events and efficiencies
Zee Ztt
0.50 0.35(stat) 0.15(sys) 0.07 0.11(stat) 0.13(sys)
tt WW,WZ,ZZ
0.04 0.03(stat) 0.06(sys) 0.10 0.04(stat) 0.10(sys)
Sbkg DATA (310 pb-1)
0.7 0.4 (stat) 0.2 (sys) 0
Selection efficiency on signal 14 for µ lt
0 13.5 for µ gt 0.
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Limits for summer 04 conferences 238 pb-1
() W.Beenakker et al PRL 83 (1999) 3780
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Present preliminary limits more luminosity (310
pb-1) and better selection cuts
tanß 5, A0 0
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Limits we can obtain in (m0,m1/2) ,and on M?o1
Susygen (scan) v3.00-43, suspect v2.3
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Other couplings ?

• We have to set limits with ?133 coupling to be
  conservative ? studied by Anne-Catherine Le-Bihan
  (IReS, France) , with eet final states.
• To see how we are sensitive at ?133 coupling with
  ee (e or µ) final states

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Results from other experiments

• DØ Run I limits in (m0, m1/2), for µ lt 0 and µ
  gt 0,
• tanß 5, 10, with ?121 and ?122 couplings.
• CDF Run I stop mass limits ? ? couplings.
• LEP limits on m?o1 gt 39 GeV and ?1 gt 103 GeV,
  for ?133 coupling, ? available for all ?
  couplings.
• H1 limits on ?1j1(j1,2) vs msquarks, and in
  (m0,m1/2),
• CMS preliminary study with ?121 and ?122
  couplings.

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CMS results with ?121 coupling
Dilepton Invariant mass with m0 200, m1/2
700. Selection at least 3 leptons (e, µ) and 2
jets (pTe gt 20 GeV, pTµ gt 10 GeV, pTjets gt 50
GeV.)
tanb 2, µ lt 0 Lint 10 fb-1.
5-sigma reach contour for ?223 0.06 (lower
curve) and ?121 0.05 (upper curve).
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Conclusion and prospects

• Anne-Catherine Le-Bihan (IReS) is working on
  ?133 coupling with eet final states,
• Daniela Kaefer (Aachen, Germany) is also working
  on ?122 coupling with µµX (e or µ) final
  states.
• We should have combined results for those 3
  couplings for Winter 05 conferences.

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Backup
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Tevatron and DØ detector
?s 2 TeV Time between collisions 400 ns.
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Central detectors view
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Some words on R-parity