CharginoNeutralino Search

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Chargino-Neutralino Search
Chargino and neutralino searches in the
tri-leptons channelAnadi Canepa Purdue
UniversityMariopaolo Giordani UC Davies
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Beyond the Standard Model
Why do we need a theory beyond the SM ?
We want to provide explanation to- EWSB
introduces new problems (quadratic
divergences)- particle masses and mixing
patterns (masses are still input
parameters)Experimental facts - dark matter-
dark energy
SUSY as a theory beyond the SM
The simplest SUSY extension of SM is MSSM- all
SM particles have a superpartner with the same
quantum numbers but different spin
- the Higgs sector contains 2
Higgs doublets
SM Boson SUSY Fermion
SM Fermion SUSY Boson
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SM vs SUSY particles
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Chargino neutralino production

• s-channel (via virtual exchange) -
  t-channel (via exchange)

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Sparticle production cross sections

• consider mSUGRA as a start- over LARGE
  PARAMETER space chargino and neutralino
  production is dominant (SUGRA report hep-ph
  0003147)

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Chargino-Neutralino Decays

• SUSY R-parity is assumed conserved- LSP is
  assumed stable (taken to be the light
  neutralino)- lepton are rare at ppbar collider
  clean signature

We are interested inthe leptonic decay ofboth
chargino and neutralino
SIGNATURE3 leptons missing energy
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Background
Background with the same signature- WZ- ZZ-
WW jet- bbbarjet- ccbar jet- ttbarjet
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How did RunI do?
RunI (PRL published) Given the integrated
luminosity of 0.1fb-1, the limits are ?BR lt
0.34 pb M chargino gt 81.5 GeV/c2 (for tan ? 2,
? -600 Gev/c2 and M squark M sgluino)
RunII - expect a integrated luminosity of
0.5fb-1 - expect ?BR sensitivity 5 times better
than in RunI
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Chargino-Neutralino Search

• Analysis outline
• understand the analysis ingredients
• signal MC studies
• DATA set to use (mainly the pt cut)
• build tools (trigger efficiences, weigth
  routines, )
• collect enough data to be searched
• background studies
• increase signal sensitivity
• find SUSY or set a limit