1. July 22 nd, 2005 A.Canepa, SUSY 2005, Durham 1 Search for chargino and neutralino in trilepton final states Anadi Canepa (Purdue University IN, USA) for the CDF Collaboration The 13 th Annual International Conference on SUperSYmmetry and Unification of the Fundamental Interactions

2. July 22 nd, 2005 A.Canepa, SUSY 2005, Durham 2 Why trilepton ? Higgsinos and gauginos mix CHARGINOS NEUTRALINOS  Low background  Easy to trigger LOW MODEL DEPENDENCE Striking signature at Hadron Collider, THREE LEPTONS In mSUGRA R p conserved scenario, LARGE MISSING TRANSVERSE ENERGY from the stable LSP

3. July 22 nd, 2005 A.Canepa, SUSY 2005, Durham 3 Best reach for the trilepton search Weakly produced 100 150 200 250 300 350 400 450 500 10 -3 1 10 -2 10 -1 10 SUSY  (pb) vs sparticle mass (GeV) T. Plehn, PROSPINO W* t-channel interferes destructively Efficiency and acceptance depend upon the scenario Scenario  Topology Best scenario for low mass gauginos  Low production cross section

4. July 22 nd, 2005 A.Canepa, SUSY 2005, Durham 4 Event topology Z* W* Leptons of 1 st, 2 nd generation are preferred Leptons of 3 rd generation are preferred Best reach for the Tevatron for low mass sleptons Chargino Decay Neutralino Decay

5. July 22 nd, 2005 A.Canepa, SUSY 2005, Durham 5 How do we investigate the different scenario ? Low tan  scenario High tan  scenario sensitive to leptonic  decay sensitive to hadronic  decay CHANNELSTATUSTRIGGER PATH  + e/  reportedHigh p T Single Lepton ee +  /e reportedHigh p T Single Lepton  + e/  OngoingLow p T Dilepton e  + e/  OngoingHigh p T Single Lepton e  + e/  OngoingLow p T Dilepton  e + track OngoingLow p T Dilepton e  + track OngoingLow p T Dilepton ee + track reportedLow p T Dilepton Low tan  scenario tan  =5, 38% High tan  scenario tan  =20, 100% Acceptance improvement High p T data-sample well understood, it also provides benchmark for the challenging low p T data-sample

6. July 22 nd, 2005 A.Canepa, SUSY 2005, Durham 6 Event kinematic Chargino and Neutralino prompt decay Leptons separated in space EWK range Typical SUSY leptons Leading lepton Next-To-Leading lepton Third lepton Lepton p T (GeV )  Asymmetric p T distribution  Lepton p T thresholds  trilepton analyses 20,8,5 GeV  dielectron + track analysis 10,5,4 GeV

7. July 22 nd, 2005 A.Canepa, SUSY 2005, Durham 7 Missing Transverse Energy (MET) e   Finding SUSY at CDF CENTRAL REGION  Had Calorimeter Muon system Drift chamber Em Calorimeter  =0  =1 Recover loss in acceptance due to cracks in the detector if we accept muons with no hits in the Muon Chamber Real MET Particles escaping detection ( ) Fake MET Muon p T or jet E T mismeasurement Additional interactions Cosmic ray muons Mismeasurement of the vertex

8. July 22 nd, 2005 A.Canepa, SUSY 2005, Durham 8 Background HEAVY FLAVOR PRODUCTION  Leptons mainly have low p T  Leptons are not isolated  MET due to neutrinos DRELL YAN PRODUCTION + additional lepton  Leptons have mainly high p T  Small real MET from  decay  Low jet activity DIBOSON PRODUCTION  Leptons have high p T  Leptons are isolated and separated  MET due to neutrinos irreducible background e    e e    The third lepton originates from  conversion   00 The third lepton is a fake lepton

9. July 22 nd, 2005 A.Canepa, SUSY 2005, Durham 9 Analysis strategy BLIND ANALYSIS performed as a COUNTING EXPERIMENT Understand the SM processes yielding the same signature Increase the Sensitivity to New Physics by identifying discriminating variables Verify the SM background in “control regions” ANALYSIS CUTS Kinematic regions where New Physics is expected to be small The kinematic region where we expect New Physics (“signal” region) is NOT investigated during the whole analysis Compare the number of predicted events to the number of observed events in the “signal” region

10. July 22 nd, 2005 A.Canepa, SUSY 2005, Durham 10 Mass selection SM background totally overwhelms New Physics Cuts in common to the 3 analyses:  M ll 106 GeV  M ll > 15 GeV  min M ll < 60 GeV (dielectron+track analysis) Rejection of J/ ,  and Z # dimuon pairs 10 3 10 -1 Dimuon events

11. July 22 nd, 2005 A.Canepa, SUSY 2005, Durham 11 Jet veto Analysis Kinematic Variable Kinematic Cut Trilepton analysesJet E T > 20 GeVn. Jets < 2 Dielectron + track analysis H T = ∑jetE Tj H T < 80 GeV Drell Yan production is reduced further in the electron analyses by angular cut  ee min M T (MET,lepton) > 10 GeV (dilelectron + track analysis) Rejection of high jet multiplicity processes

12. July 22 nd, 2005 A.Canepa, SUSY 2005, Durham 12 MET selection Still BLIND Can we look at the “signal” region ? Kinematic Cut Example SUSY Signal TOT BACKGROUND Number of trilepton events 0.48  0.022.85  0.27 Invariant Mass0.42  0.021.06  0.18 Jet Multiplicity0.42  0.021.04  0.18 MET0.37  0.020.09  0.03 Trilepton Analysis (muon based) L=346 pb -1 In R p conserved searches, key quantity is MET Distinguish SUSY from SM by MET > 15 GeV

13. July 22 nd, 2005 A.Canepa, SUSY 2005, Durham 13 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) Control Region with 2  Total predicted background Observed data Z veto, high MET, n. Jets < 2 522  79538 Z mass, high MET, n. Jets > 1 1.9  0.92 Z mass window 3178  5413168 Trilepton Analysis (muon based) L=346 pb -1 Invariant Mass 15 76 106 10 15 ?? Z + fake DY +  Diboson MET

14. July 22 nd, 2005 A.Canepa, SUSY 2005, Durham 14 Control regions Very good agreement between SM prediction and observed data Trilepton analysis ee + e/  Trilepton analysis  + e/ 

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

16. July 22 nd, 2005 A.Canepa, SUSY 2005, Durham 16 Results Look at the “SIGNAL” region Analysis Total predicted background Example SUSY Signal Observed data Trilepton (  +l) 0.09  0.030.37  0.050 Trilepton (ee+l) 0.17  0.050.49  0.060 Dielectron +track 0.48  0.070.36  0.272 DYWW/ZZWZ/  *t-tbar 0.25  0.17 0.062  0.024 0.032  0.005 0.010  0.007 Details about the dielectron + track analysis

17. July 22 nd, 2005 A.Canepa, SUSY 2005, Durham 17 Leading electron e +, p T = 41 GeV Next-to-leading e -, p T = 12 GeV MET, 45 GeV Isolated track, p T = 4 GeV Muon? Candidate event ? Mass OS141.6 GeV Mass OS227.0 GeV In the dielectron + track analysis, we observe one interesting event

18. July 22 nd, 2005 A.Canepa, SUSY 2005, Durham 18 Summary 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 )

19. July 22 nd, 2005 A.Canepa, SUSY 2005, Durham 19 Outlook We hope chargino and neutralino are light enough for us to find them ! Ellis, Heinemeyer, Olive, Weiglein, hep- ph\0411216 CMSSM The results of  2 fits based on the current experimental results for the precision observables M W, sin 2  eff, (g-2) , BR(b  s  ).