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SUSY SEARCHES AT THE TEVATRON

SUSY SEARCHES AT THE TEVATRON. Xavier Portell (On behalf of CDF and D0 Collaborations). HCP (Duke, NC) May 2006. Chicago . Booster. CDF. DØ. Tevatron. p sou rce. Main Injector. THE TEVATRON. p-pbar collider: 36x36 bunches at 396 ns crossing time.

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SUSY SEARCHES AT THE TEVATRON

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  1. SUSY SEARCHES AT THE TEVATRON Xavier Portell (On behalf of CDF and D0 Collaborations) HCP (Duke, NC) May 2006

  2. Chicago  Booster CDF DØ Tevatron p source Main Injector THE TEVATRON p-pbar collider: 36x36 bunches at 396 ns crossing time • s = 1.96 TeV (Run I 1.8TeV ) Tevatron, CDF and D0 were highly upgraded in Run II. Great performance: 1.6 fb-1 delivered 1.3 fb-1 to tape Data collecting efficiencies ~ 85%

  3. WHY DO WE NEED SUSY? Q|Boson> = Fermion SUSY: The SM works very well... but there exist some unresolved problems: Q|Fermion> = Boson • The introduction of SUSY have very interesting implications: • Solves the hierarchy problem • Unification of forces at GUT scale • Provides a Dark Matter candidate • ... • Mass hierarchy problem • Unification • Dark Matter • Matter-antimatter asymmetry But SUSY also imply new undiscovered particles...

  4. SUSY BREAKING Symmetry  Need to be broken  determines phenomenology One of the preferred models: mSUGRA • New superfields in the “hidden” sector • Interact gravitationally with MSSM • Soft SUSY breaking • Only 5 parameters at SUSY scale m0: common scalar mass at GUT m1/2: the common gaugino mass at GUT tanb: Ratio of Higgs vaccum expectation values A0: Trilinear coupling Sign(m): Higgs mass term

  5.  l121 ~ ~  e  0 1 e- R-PARITY Most general SUSY lagrangian  Leptonic and Baryonic number violation in the superpotential • land l’ violate leptonic number andl’’ the baryonic number • ijk denote the families involved New quantum number: Rp=(-1)3(B-L)+2s 1 2 1 SM particles: Rp=1 Superpartners: Rp=-1 When Rp is conserved: • Superpartners are pair produced • Lightest SUSY Particle (LSP) Dark Matter candidate!

  6. WHY AT THE TEVATRON? T. Plehn, PROSPINO Tevatron: 1.96 TeV LHC: 14 TeV Cross Section (pb) T. Plehn, PROSPINO  increase by 3-4 orders of magnitude w.r.t. Tevatron.  comparable to Tevatron (and with more background). Cross Section (pb) Good prospects for finding SUSY at the Tevatron! 100 events per fb-1

  7. OUTLINE CHARGINOS AND NEUTRALINOS SQUARKS AND GLUINOS RPC MET+jets 3-leptons GMSB CHARGINO/NEUTRALINO gg + MET RPV CHARGINO/ NEUTRALINO STOP b-jets and taus 4-leptons INDIRECT SEARCHES: BSmm INDIRECT

  8. OUTLINE

  9. SQUARKS AND GLUINOS DIRECT SQUARK-GLUINO PRODUCTION: Strong interaction: large production expected DECAY: Missing ET Multiple jets Missing ET (MET) + jets Missing ET Optimized for three cases: 2-jets (when Mgl>Msq) 3-jets (when Mgl~Msq) 4-jets (when Mgl<Msq) - Always 3 or more jets - Optimization for three different ranges of gluino masses. Studied an mSUGRA scenario with first4 flavors degenerate(sbottom/stop not considered) Backgrounds are challenging (specially QCD)

  10. SQUARKS AND GLUINOS Distributions after all cuts for CDF and D0 agree with data in all cases. 4-jet optimization Mgl~240 GeV/c2 Mgl~507 GeV/c2 3-jet optimization Mgl~Msq~330 GeV/c2 CDF background contributions after all the cuts.

  11. SQUARKS AND GLUINOS: LIMITS CDF:Includes the theoretical uncertainties when calculating the observed limit D0: 310 pb-1, A0=0, m<0 and tanb=3 CDF: 371 pb-1, A0=0, m<0 and tanb=5 D0:Reduce theoretical cross section by 1s (more conservative) Mgl > 387 GeV/c2 (when Mgl~Msq) Mgl > 241 GeV/c2 ; Msq > 325 GeV/c2

  12. Depending on the mass: • Heavy: • Medium: • Light: 3rd GENERATION SQUARKS SUSY: Predicts left- and right-handed scalar partner eigenstates for each SM fermion As 3rd generation is heavier, stop and sbottom could be the lightest SUSY particles. Important to have specific analyses for them! SBOTTOM Signatures of 2 or 4 b-jets and MET STOP A Light stop is preferred (consistent with baryogenesis) Balazs, Carena, Wagner (hep-ph/0403224) Soft jets (experimental challenge)

  13. (m , m ) = (140, 80) GeV/c2 SBOTTOM RESULTS SELECTION CRITERIA • Good agreement data/MC • Exclude sbottom masses up to 200 GeV (depending on neutralino mass) • At least two jets, one b-tagged. • Three different jet/MET thresholds (increasing sbottom mass): • ET1st > 40-70 GeV ET2nd> 15-40 GeV • MET > 60-100 GeV ET1st > 40 GeV ET2nd> 15 GeV MET > 60 GeV

  14. STOP • D0: 2 different analyses to improve sensitivity: em, mm • em analysis: optimized for different Dm= (Mstop – Msneutrino) values • Missing ET > 15 GeV • Topological cuts The sneutrino usually decays into neutrino and neutralino (MET) Numbers compatible with SM Great improvement with respect to Run I (excluding up to the top mass)

  15. OUTLINE

  16. CHARGINOS AND NEUTRALINOS PRODUCTION Mix to form the mass states Always one lepton from + Missing ET Always two leptons from In mSUGRA: M ~ M ~ 2 M Clean signature and relatively high cross sections GOLDEN CHANNEL We have always 2 like-sign leptons (one from each superpartner)

  17. IMPORTANT ANALYSES VARIETY • 3 leptons (ee+l, mm+l, em/me+l) • 2 leptons + track • 2 like-sign (LS) leptons (ee,mm,em) CHARGINOS AND NEUTRALINOS The third lepton tends to be very soft tanb determines the lepton flavor composition Cuts in lepton PT: PT1st~20 GeV/c PT2nd~10 GeV/c taus dominate Low pT zone Different trigger paths and cut optimizations for e/m and tracks in general

  18. CHARGINOS AND NEUTRALINOS • Minimum pT for the 2 leading leptons • Dilepton mass and angle cuts (avoid Z and Drell-Yan) • Small jet activity • Missing transverse energy significant Requirements to reduce SM background (DY, diboson, conversions...) Observed/Expected Events All is compatible with SM... D0 CDF mt+t et+t

  19. CHARGINOS AND NEUTRALINOS Low tanb and slepton mass degenerate Low tanb and no slepton mixing Different luminosities, different number of analyses and slightly different scenarios M > 117 GeV/c2 M > 127 GeV/c2 Results are model dependent (for e.g. with slepton mixing the acceptance is worse and there are no new constraints yet) • Beyond LEP (in these scenarios) • More luminosity is being added • Already implementing some improvements...

  20. OUTLINE

  21. GMSB: gg+MET In Gauge Mediated Supersymmetry Breaking (GMSB) model the neutralino is the NLSP and the gravitino the LSP (~1 keV/c2). D0 with 760 pb-1: • 2 photons (ET>25 GeV) • MET > 45 GeV • SM expect: 2.1 events • Observation: 1 event NLO Previous D0 result (263 pb-1) New D0 result (760 pb-1) Neutralino Chargino New constraints for this process L is the only dimensioned parameter of the GMSB model.

  22. OUTLINE

  23. RPV: CHARGINO/NEUTRALINO • Onlyfirst term of WRPV is considered (protect proton lifetime) • Charge current universality  |l|<0.135 GeV • RPV vertex: only in the last decay. • The decay is inside the detector • In general: l121 > l122 >> l133 • CDF: performing analyses only in l121 andl122 • D0: analysing also l133 (high tanb, low m0) i,j,k denote the leptonic families involved. ASSUMPTIONS A pair of  at least 4 leptons and two neutrinos Also optimizing for 3 leptons to improve acceptance l1210  eeee, eeem, eemm l1220  mmmm, mmme, mmee Only one RPV at a time Low background just for asking 4 leptons or more!

  24. RPV: 4 LEPTONS Probability to see >=5 with 2.9  0.8 is 17% Very low background! No event found after cuts

  25. RPV: STOP • 2 b-jets • 1 t hadronic (64.8%) • 1 t semi-leptonic (35.2%) RPV vertex CHALLENGE: t identification Jets and leptons  t misidentification Used Ztt for hadronic t ID: Eff ~ 56% RPV vertex Expected events: 2.2 Observed events: 2 (1e + 1m) New mass limits are obtained with 322 pb-1

  26. OUTLINE

  27. INDIRECT SEARCHES: BSmm SM: Bs->mm is heavily suppressed: SUSY: BR enhancement by 1-3 orders of magn. (Buchalla & Buras, Misiak & Urban) (Babu, Kolda: hep-ph/9909476+ many more) New CDF result: 780 pb-1 Using B+J/ K+ for normalization R. Dermisek et al. hep-ph/0507233 (2005) High resolution! s(Mmm) ~ 0.23 MeV New limits at 95% C.L: BR(Bsmm) < 1.0·10-7 Found 1 event; expected background 0.90.3

  28. DISCLAIMER • Due to time constraints I couldn’t cover all the analyses for both detectors. • Some of the most interesting analyses, not covered here, are: • Stopped gluinos (split SUSY) (350 pb-1) • Long lived charginos (AMSB) (380 pb-1)  This topic will be covered in the next talk • Resonant slepton production (RPV) (380 pb-1) • sneutrinoem (RPV) (344 pb-1) • You can find them all at the CDF or D0 webpages: • http://www-cdf.fnal.gov/physics/exotic/exotic.html • http://www-d0.fnal.gov/Run2Physics/WWW/results/np.htm

  29. SUMMARY • Tevatron and detectors are performing very well: • 1.6 fb-1 delivered (collected: 1.3 fb-1) • Upgrades have been performed during this shutdown • This week Tevatron will start again fully operational and 2 fb-1 benchmark is getting closer. • Plenty of SUSY analyses going on at CDF/D0 detectors. They are being improved with the addition of new data. • No SUSY particles have been discovered yet but both direct and indirect analyses are constraining the SUSY parameter space. Tevatron will keep constraining the SUSY parameters until the LHC era... and perhaps a surprise is found!

  30. BACKUPS

  31. Different 3-Leptons Scenarios In Standard mSugra the BR into taus is enhanced smaller acceptance

  32. CDF 3-Leptons Analyses No third lepton requirement => Higher acceptance Use e/mu only =>Very small backgrounds Sensitive to taus as 3rd lepton => Keeps acceptance at high tan

  33. ?? SIGNAL REGION 15 10 15 76 106 M(  ) CDF 3-Leptons Control Regions • Drell-Yan • WZ • ZZ • ttbar • Fakes -SUSY • DATA MET • Drell-Yan • Dibosons • ZZ • bbbar - SUSY • DATA L=607 pb-1 N events/2 GeV/c 2 MET (GeV) Dielectron Invariant Mass(GeV/c2) LS-dilepton analysis has additional Control Regions to test conversion removal Dimuon PT(GeV/c)

  34. CDF 3-electron Event

  35. 3-LEPTONS: PROJECTIONS

  36. Bsmm: PROJECTIONS

  37. SQUARKS/GLUINOS: FUTURE

  38. SQUARKS AND GLUINOS

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