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Search for SUGRA at

Search for SUGRA at. Silke Duensing SUSY 2003, June 10 th. u. p. d. p. u. q. ~1 TeV. ~1 TeV. q. u. u. d. Interactions. u. p. d. p. u. q. ~1 TeV. ~1 TeV. q. u. u. d. SUGRA@Tevatron. Sparticles are produced in pairs

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Search for SUGRA at

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  1. Search for SUGRA at Silke Duensing SUSY 2003, June 10 th

  2. u p d p u q ~1 TeV ~1 TeV q u u d Interactions

  3. u p d p u q ~1 TeV ~1 TeV q u u d SUGRA@Tevatron Sparticles are produced in pairs R-parity conservation: decay into the “partner” +LSP LSP->missing energy, mET at Tevatron

  4. Typical cross-sections (pb) Squark/gluino pair production Jets + Missing ET is generic signature for squark/gluino production in SUGRA m [GeV]

  5. Typical cross-sections (pb) Jets + Missing ET • Selection : >=2 jets + mET • Trigger: • >=1 jet with pT > 65 GeV • Offline: • leading jet has pT > 100 GeV , leading two jets are central • insures full efficiency of trigger • mET calculated by adding all calorimeter towers with E>200 MeV • Used are (the first) ~ 4 pb-1 m [GeV]

  6. Fit interval 40-65 GeV Jets + Missing ET • Selection : >=2 jets + mET • Background (I) - Physics: • PYTHIA-generated and fully simulated samples for physics backgrounds (real mET) • Background (II) - Instrumental: • Ensure good quality of data • Require |df|(mET, jet1,2)>0.15 • reject events where mET results from mismeasured Jet pT • fit to low mET region to estimate QCD background • mismeasured mET

  7. Fit interval 40-65 GeV Jets + Missing ET • Error is sum of: • Statistical error of QCD bkg • From error of fit parameters • Systematic error of QCD bkg • From different fit ranges • (much smaller) statistics of MC sample of physics background

  8. Final States with Leptons • Neutralinos/charginos • trilepton channel • Electron-muon channel • Low SM background WW, ttbar, Z/g* ->tt • gain compared to Run I for DØ: improved particle identification • Provides model independent limit on NP cross section

  9. em inclusive search • require pT >15 GeV for both leptons (e/) • physics background from Monte Carlo • Instrumental background (fake rates) from data • Quote cross-section limits as function of mET PT mET Njet

  10. em inclusive Ø No jets ET > 15 GeV No missing ET cut ~30 pb-1

  11. em - Limits on New Physics Z tt dominates 100 fb A(WWem) = 17% Instrumental + WW

  12. Chargino-Neutralino production Typical cross-sections (pb) • Tri-Lepton signature • Look at lee 2 points in Minimal SUGRA m≈2m 2m ≈90 and 125 GeV

  13. Tri-lepton eel - pre-selection • 1) At least 2 electrons (leading e pT>15 GeV • 2nd e pT>10 GeV) • Start from di-electron sample • understand trigger, reconstruction, simulation • verify determination of QCD fake background • from data with inverted identification cuts L = 42.0 pb-1

  14. Tri-lepton eel-event selection • 1) At least 2 electrons (leading e pT>15 GeV • 2nd e pT>10 GeV) • 10<Mee<70 GeV • 3) MT(e,mET)>15 GeV

  15. Tri-lepton eel- cross section limit • 1) At least 2 electrons (leading e pT>15 GeV • 2nd e pT>10 GeV) • 2) 10<Mee<70 GeV • 3) MT(e,mET)>15 GeV • 4) A third isolated track PT>5 GeV,|h|<3.0 • 5) mET>15 GeV typical selection efficiency for SUGRA 2-4%

  16. Tri-lepton eel- cross section limit • 1) At least 2 electrons (leading e pT>15 GeV • 2nd e pT>10 GeV) • 2) 10<Mee<70 GeV • 3) MT(e,mET)>15 GeV • 4) A third isolated track PT>5 GeV,|h|<3.0 • 5) mET>15 GeV • s x BR(3lepton) < 3.5 pb (95% CL) ……sensitivity still about factor of 7 away from extending excluded area in the parameter space work in progress more data

  17. Trilepton - eee mET event

  18. Summary • The Run II Era for searches has begun at DØ… • with a search for squarks/gluinos in Jet mET • with a look at the em final state • with a trilepton - search containing electrons • So far - nothing beyond SM … but: • all this will be updated with improved analyses, more channels and more luminosity

  19. Highest mET em event Missing ET = 33.5 GeV -, PT = 45 GeV e+, PT = 21 GeV

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