Search for chargino and neutralino in trilepton final states

1. Search for chargino and neutralino in trilepton final states Anadi Canepa(Purdue University IN, USA)for the CDF Collaboration The 13th Annual International Conference on SUperSYmmetry and Unification of the Fundamental Interactions A.Canepa, SUSY 2005, Durham

2. Why trilepton ? Higgsinos and gauginos mix CHARGINOS NEUTRALINOS Striking signature at Hadron Collider, THREE LEPTONS In mSUGRA Rp conserved scenario, LARGE MISSING TRANSVERSE ENERGY from the stable LSP • Low background • Easy to trigger LOW MODEL DEPENDENCE Golden Plate at Hadron Collider A.Canepa, SUSY 2005, Durham

3. T. Plehn, PROSPINO W* 10 SUSY  (pb) vs sparticle mass (GeV) 1 10-1 10-2 10-3 100 150 200 250 300 350 400 450 500 Best reach for the trilepton search • Low production cross section Weakly produced t-channel interferes destructively Best scenario for low mass gauginos Efficiency and acceptance depend upon the scenario Scenario  Topology Very Challenging Search A.Canepa, SUSY 2005, Durham

4. Z* W* Event topology Leptons of 3rd generation are preferred Leptons of 1st, 2nd generation are preferred Chargino Decay Neutralino Decay Best reach for the Tevatron for low mass sleptons A.Canepa, SUSY 2005, Durham

5. Acceptance improvement Low tan scenario tan=5 , 38% High tan scenario tan=20, 100% How do we investigate the different scenario ? sensitive to leptonic  decay Low tan scenario sensitive to hadronic  decay High tan scenario High pT data-sample well understood, it also provides benchmark for the challenging low pT data-sample A.Canepa, SUSY 2005, Durham

6. Leading lepton Next-To-Leading lepton • Asymmetric pT distribution Third lepton Chargino and Neutralino prompt decay Lepton pT (GeV) Typical SUSY leptons Leptons separated in space EWK range Event kinematic Lepton pT thresholds • trilepton analyses 20,8,5 GeV • dielectron + track analysis 10,5,4 GeV A.Canepa, SUSY 2005, Durham

7. =0 e =1 Muon system  Recover loss in acceptance due to cracks in the detector if we accept muons with no hits in the Muon Chamber  Missing Transverse Energy (MET) Drift chamber Em Calorimeter Had Calorimeter Finding SUSY at CDF CENTRAL REGION  Real MET • Particles escaping detection () Fake MET • Muon pT or jet ET mismeasurement • Additional interactions • Cosmic ray muons • Mismeasurement of the vertex A.Canepa, SUSY 2005, Durham

8. e e The third lepton originates from  conversion    e  0 The third lepton is a fake lepton     Background • DRELL YAN PRODUCTION + additional lepton • Leptons have mainly high pT • Small real MET from  decay • Low jet activity • DIBOSON PRODUCTION • Leptons have high pT • Leptons are isolated and separated • MET due to neutrinos irreducible background HEAVY FLAVOR PRODUCTION • Leptons mainly have low pT • Leptons are not isolated • MET due to neutrinos A.Canepa, SUSY 2005, Durham

9. Analysis strategy The kinematic region where we expect New Physics (“signal” region) is NOT investigated during the whole analysis ANALYSIS CUTS Kinematic regions where New Physics is expected to be small Compare the number of predicted events to the number of observed events in the “signal” region A.Canepa, SUSY 2005, Durham

10. Dimuon events 103 # dimuon pairs 10-1 Mass selection SM background totally overwhelms New Physics • Cuts in common to the 3 analyses: • Mll<76 GeV & Mll>106 GeV • Mll> 15 GeV • min Mll< 60 GeV (dielectron+track analysis) Rejection of J/,  and Z A.Canepa, SUSY 2005, Durham

11. Jet veto Rejection of high jet multiplicity processes • Drell Yan production is reduced further in the electron analyses by • angular cut ee • min MT(MET,lepton) > 10 GeV • (dilelectron + track analysis) A.Canepa, SUSY 2005, Durham

12. MET selection In Rp conserved searches, key quantity is MET Distinguish SUSY from SM by MET > 15 GeV Trilepton Analysis (muon based) L=346 pb-1 Still BLIND Can we look at the “signal” region ? A.Canepa, SUSY 2005, Durham

13. ?? MET Diboson 10 15 DY +  Z + fake 15 76 106 Invariant Mass Data understanding • Each control region is investigated • with different jet multiplicity to check NLO processes • with 2 leptons requirement (gain in statistical power) • with 3 leptons requirement (signal like topology) Trilepton Analysis (muon based) L=346 pb-1 A.Canepa, SUSY 2005, Durham

14. Control regions Very good agreement between SM prediction and observed data Trilepton analysis ee + e/ Trilepton analysis ee + e/ Trilepton analysis  + e/ A.Canepa, SUSY 2005, Durham

15. Systematic uncertainty • Major systematic uncertainties affecting the measured number of events • Signal • Lepton ID 5% • Muon pT resolution 7% • Background • Fake rate 5% • Jet Energy Scale 22% • Common to both signal and background • Luminosity 6% • Theoretical Cross Section 6.5-7% A.Canepa, SUSY 2005, Durham

16. Results Look at the “SIGNAL” region Details about the dielectron + track analysis A.Canepa, SUSY 2005, Durham

17. Next-to-leading e-, pT = 12 GeV Leading electron e+, pT = 41 GeV Isolated track, pT = 4 GeV Muon? MET, 45 GeV Candidate event ? In the dielectron + track analysis, we observe one interesting event A.Canepa, SUSY 2005, Durham

18. Summary Trilepton is an excellent signature for Physics Beyond the SM • Sensitive to CHARGINO & NEUTRALINO associated production • 8 analyses are ongoing and 3 have being shown in this talk • Data agree with the SM background  No excess • Not sensitive in mSUGRA yet … Acceptance and luminosity are the key for this search • The acceptance will be greatly improved by • adding the additional channels • loosing the lepton identification criteria  very low background • …. • Tevatron recently delivered 1 fb-1 (analyses presented used 220-350 pb-1) A.Canepa, SUSY 2005, Durham

19. Outlook Ellis, Heinemeyer, Olive, Weiglein, hep-ph\0411216 CMSSM The results of 2 fits based on the current experimental results for the precision observables MW, sin2eff, (g-2), BR(bs). We hope chargino and neutralino are light enough for us to find them ! A.Canepa, SUSY 2005, Durham