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Searches for Supersymmetry at the Tevatron

Searches for Supersymmetry at the Tevatron. Liverpool HEP Seminar Thursday 15th December 2005. Giulia Manca, University of Liverpool. “Supersymmetry”, by Karl Hager From the artist’s website http://www.cassetteradio.com/cubagallery/hagen.htm

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Searches for Supersymmetry at the Tevatron

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  1. Searches for Supersymmetry at the Tevatron Liverpool HEP Seminar Thursday 15th December 2005 Giulia Manca, University of Liverpool

  2. “Supersymmetry”, by Karl Hager From the artist’s website http://www.cassetteradio.com/cubagallery/hagen.htm “…I try to leave the intention minimized while maintaining an element of exploratory desperation.” http://www.cassetteradio.com/cubagallery/hagen.htm

  3. Outline • Supersymmetry • The Tevatron and its experiments • Searching for Chargino and Neutralino • Conclusions • Outlook Giulia Manca, University of Liverpool

  4. Supersymmetry: Introduction ~ f f H H H H ~ f f • New symmetry fermions-bosons: • SM fermion  SUSY boson • SM boson  SUSY fermion • Ideated to cancel quadratic divergencies in the Higgs self coupling energy • Sparticles not observed in nature => Susy must be broken! Giulia Manca, University of Liverpool

  5. Supersymmetry: models Determines the SUSY Mass spectrum! • Different mechanisms of susy breaking lead to different models Giulia Manca, University of Liverpool

  6. Supersymmetry: particles g ~ G ci 4 neutralinos 2 charginos G c0i 1. mSugra and AMSB: c01LSP, stable 3. Rp (RPV): LSP decays into SM particles ~ 2. GMSB: G LSP,stable +1 (SM particles) R-Parity Quantum Number-> -1 (Susy particles) Giulia Manca, University of Liverpool

  7. Supersymmetry: why ? • Solves “Hierarchy Problem” • ProvidesGrand Unification Theoryat the 1016 GeV scale • Consistent with results fromPrecision Datafits • Rp Conserving models providegoodDark Matter Candidate(LSP) New Top Mass 172.7 GeV/c2 Giulia Manca, University of Liverpool

  8. Supersymmetry & Dark Matter • Evidence for Dark Matter • galaxy rotation • fluctuations in the cosmic microwave background (WMAP) • In mSugra and with Rp conserved and EW radiative corrections, • 4 main regions where neutralino fulfills the WMAP relic density M1/2 (GeV) • bulk region (low m0 and m1/2) • stau coannihilation region m  mstau • hyperbolic branch/focus point (m0 >> m1/2) • funnel region (mA,H 2m) M0(GeV) Giulia Manca, University of Liverpool

  9. Supersymmetry & Dark Matter HOWEVER: MORE OPTIONS WITH LESS CONSTRAINED MODELS • Evidence for Dark Matter • galaxy rotation • fluctuations in the cosmic microwave background (WMAP) • In mSugra and with Rp conserved and EW radiative corrections, • 4 main regions where neutralino fulfills the WMAP relic density H. Baer, A. Belyaev, T. Krupovnickas, J. O’Farrill, JCAP 0408:005,2004 M1/2 • bulk region (low m0 and m1/2) • stau coannihilation region m  mstau • hyperbolic branch/focus point (m0 >> m1/2) • funnel region (mA,H 2m) M0 Giulia Manca, University of Liverpool

  10. Supersymmetry: how ? Rp : LSP : c c± (fb) GMSB: 2 LSPs 1012 Remember : VERY SMALL cross sections !! 104 10 Wide range of signatures: look for SuSy specific signatures or excess in SM ones; examples: • Large Missing Energy ET • Isolated leptons • Multijets • Diphotons Giulia Manca, University of Liverpool

  11. The Tevatron design goal Still long way to go! p p at ECM 1.96 TeV base goal • High Luminosity • Tevatron 1 fb-1! • CDF and D0 running at high efficiency Mar01-Jul04 350pb-1 Giulia Manca, University of Liverpool

  12. Charginos and Neutralinos

  13. Why Charginos and Neutralinos ? • They are light(~ 100-500 GeV/c2) • Squarks and gluinos too heavy for the Tevatron • They decay giving striking signatures • In mSugra : 3 isolated leptons + ET • In GMSB : 2 photons + ET • In AMSB : long-lived particles • In Rp models : >3 leptons (and many more signatures in each model depending on the parameters !) / / / Giulia Manca, University of Liverpool

  14. The trilepton signal CHARGINOS NEUTRALINOS Higgsinos and gauginos mix 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 SIGNAL AT THE TEVATRON !! Giulia Manca, University of Liverpool

  15. Existing Limits : LEP SM Higgs Limits Slepton Limits Chargino-Limits LEP I Precision measurements Theoretically forbidden (i.e. M1(GUT)=M2(GUT)=M3(GUT)=m1/2) Giulia Manca, University of Liverpool

  16. ADLO exclusion plots Giulia Manca, University of Liverpool

  17. Chargino-Neutralino production… T. Plehn, PROSPINO SUSY (pb) vs sparticle mass(GeV/c2) for √s=1.96 TeV W* 10 1 c c± 10-1 10-2 10-3 100 150 200 250 300 350 400 450 500 • Low cross section (weakly produced) t-channel interferes destructively Tevatron sensitive to the BULK region in WMAP data Giulia Manca, University of Liverpool

  18. …and decay Z* W* Leptons of 3rd generation are preferred Leptons of 1st, 2nd generation are preferred Chargino Decay Neutralino Decay Best reach for the Tevatron for mass sleptons~mass chargino => BR (3l) enhanced Giulia Manca, University of Liverpool

  19. Trileptons at CDF

  20. How to investigate the different scenarios? Acceptance improvement Low tan scenario tan=5 , 38% High tan scenario tan=20, 100% sensitive to leptonic  decay Low tan region High tan region sensitive to hadronic  decay High pT data-sample benchmark to understand low pT data-sample Giulia Manca, University of Liverpool

  21. Event kinematic Leading lepton Next-To-Leading lepton Third lepton Chargino and Neutralino prompt decay Lepton pT (GeV) Typical SUSY leptons Leptons separated in space EWK range Lepton pT thresholds • trilepton analyses 20,8,5 GeV • dielectron + track analysis 10,5,4 GeV Giulia Manca, University of Liverpool

  22. Finding SUSY at CDF =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 CENTRAL REGION  Real MET • Particles escaping detection () Fake MET • Muon pT or jet ET mismeasurement • Additional interactions • Cosmic ray muons • Mismeasurement of the vertex Giulia Manca, University of Liverpool

  23. Backgrounds e e    e  0 The third lepton is a fake lepton     Backgrounds • DIBOSON (WZ,ZZ) PRODUCTION • Leptons have high pT • Leptons are isolated and separated • MET due to neutrinos irreducible background • DRELL YAN PRODUCTION + additional lepton • Leptons have mainly high pT • Small MET • Low jet activity HEAVY FLAVOUR PRODUCTION • Leptons mainly have low pT • Leptons are not isolated • MET due to neutrinos The third lepton originates from  conversion e e Giulia Manca, University of Liverpool

  24. Analysis Strategy COUNTING EXPERIMENT • Optimiseselection criteria for best signal/background value; • Apply selection criteria to the data • Definethe signal region and keep it blind • Test agreement observed vs. expected number of events in orthogonal regions (“control regions”) • Look in the signal region and count number of SUSY events !! • Or set limit on the model Giulia Manca, University of Liverpool

  25. Selection criteria: (I) Mass # dimuon pairs Rejection of J/,  and Z Dimuon events • Mll<76 GeV & Mll>106 GeV • Mll> 15 GeV • min Mll< 60 GeV (dielectron+track analysis) Giulia Manca, University of Liverpool

  26. (II) DeltaPhi(l,l) + Jet veto Rejection of DY and high jet multiplicity processes Giulia Manca, University of Liverpool

  27. (III) MET selection Further reducing DY by MET > 15 GeV Trilepton Analysis (muon based) L=346 pb-1 …Still BLIND ! Giulia Manca, University of Liverpool

  28. Understanding of the Data ?? MET Diboson 10 15 DY +  Z + fake 15 76 106 Invariant Mass • 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 SIGNAL REGION Very good agreement between SM prediction and observed data Giulia Manca, University of Liverpool

  29. Systematic uncertainty • Major systematic uncertainties affecting the measured number of events • Signal • Lepton ID 5% • Muon pT resolution 7% • Background • Fake lepton estimate method 5% • Jet Energy Scale 22% • Common to both signal and background • Luminosity 6% • Theoretical Cross Section 6.5-7% Z->ee MC Giulia Manca, University of Liverpool

  30. Results ! Look at the “SIGNAL” region Details about the dielectron + track analysis Giulia Manca, University of Liverpool

  31. Candidate event ? Next-to-leading e-, pT = 12 GeV Leading electron e+, pT = 41 GeV Isolated track, pT = 4 GeV Muon? MET, 45 GeV In the dielectron + track analysis, we observe one interesting event Giulia Manca, University of Liverpool

  32. Trileptons at DO

  33. DO detector =1.0 =0 =1.0 =2.0 =3.0 =3.6 • Coverage to muons up to eta~2 Giulia Manca, University of Liverpool

  34. Chargino and Neutralino in 3+ET • sxBR~0.2 pb • Very clean signature • SM background very small ! InmSUGRA:3leptons+ET 6 analyses: -2l(l=e,m,t)+isolated track or mm - ET and topological cuts (M,Df, MT) M(et) (GeV/c2) Giulia Manca, University of Liverpool

  35. Chargino Neutralino Limits ~ ~ ~ mSUGRA:M(c±)≈M(c02)≈2M(c01) “3l-max” • M()>M(c02) • Nosleptonmixing Limits: • sxBR<0.2pb • M(c±1)>116GeV/c2 “HeavySquarks” • M(c±)≈M(c02)3M(q) • sxBR<0.2pb • M(c±1)>128GeV/c2 “Largem0” • M()>>M(c02,c±) • Nosensitivity ~ ~ mSugra optimistic scenario A0=0 ~ ~ ~ ~ ~ ~ ~ ~ ~ Start testing above LEP limit for mSUGRA-but LEP Model Independent !! Giulia Manca, University of Liverpool

  36. Summary and Outlook: Chargino and Neutralino in mSugra TRILEPTONS SIGNAL: • CDF and D0 analysed first half of data and observed no excess :( • Set limit already beyond LEP results ! (although model dependent ) • 1 fb-1 of data collected and ready to be analysed M() <170 GeV) • With 4-8 fb-1 by the end of RunII we should be sensitive to Chargino masses up to ~250 GeV andsxBR~ 0.05-0.01 pb !! Ellis, Heinemeyer, Olive, Weiglein, hep-ph\0411216 Favoured by EW precision data Giulia Manca, University of Liverpool

  37. Charginos and Neutralinosin GMSB

  38. Why Charginos and Neutralinos ? • They are light(~ 100-500 GeV/c2) • Squarks and gluinos too heavy for the Tevatron • They decay giving striking signatures • In mSugra : 3 isolated leptons + ET • In GMSB : 2 photons + ET • In AMSB : long-lived particles • In Rp models : >3 leptons (and many more signatures in each model depending on the parameters !) / / / Giulia Manca, University of Liverpool

  39. Motivation: Run I CDF Event • Run I event: • 2 e, 2 g and Et=56 GeV • SM expectaction: 10-6 Events • Interpretations in GMSB: • Selectron • Chargino/Neutralino • Visible in inclusive diphoton Et spectrum • Searched by Tevatron Run II, LEP and HERA Phys.Rev.Lett.81:1791-1796,1998 Giulia Manca, University of Liverpool

  40. Chargino Neutralino in gg+ET ~ In GMSB: 2 photons+ET D0(CDF)Eventselection: -2photonsET->20(13)GeV -ET>40(45)GeV CDF‡ and D0# combined result: m(c±)>209 GeV/c2 ‡Phys.Rev.D.71,3 031104(2004) #Phys. Rev. Letters 94, 041801(2005) Giulia Manca, University of Liverpool

  41. Charginos and Neutralinosin AMSB

  42. Why Charginos and Neutralinos ? • They are light(~ 100-500 GeV/c2) • Squarks and gluinos too heavy for the Tevatron • They decay giving striking signatures • In mSugra : 3 isolated leptons + ET • In GMSB : 2 photons + ET • In AMSB : long-lived particles • In Rp models : >3 leptons (and many more signatures in each model depending on the parameters !) / / / Giulia Manca, University of Liverpool

  43. Charginos in AMSB • In the AMSB scenario (c01 LSP) • c±1is the NLSP (Next-to-Lightest-Supersymmetric Particle) • lives long enough to decay outside the detector; • c and the BR depend almost entirely upon the mass difference c±1-c01 • c±1-> c01 M( Giulia Manca, University of Liverpool

  44. Champs 100 GeV Staus 100 GeV Higgsino-like Chargino 100 GeV Gaugino-like Chargino CHArged Massive stable Particles: -electrically charged -massive->speed<<c -lifetime long enough to decay outside detector Event Selection: -2 muons Pt> 15 GeV, isolated -Speed significantly slower than c No SM Background!!->from DATA Limits in AMSB: champ = c ±1 • M(c±1)>174 GeV/c2 ~ ~ Giulia Manca, University of Liverpool

  45. Charginos and Neutralinosin Rp violating

  46. Why Charginos and Neutralinos ? • They are light(~ 100-500 GeV/c2) • Squarks and gluinos too heavy for the Tevatron • They decay giving striking signatures • In mSugra : 3 isolated leptons + ET • In GMSB : 2 photons + ET • In AMSB : long-lived particles • In Rp models : >3 leptons (and many more signatures in each model depending on the parameters !) / / / Giulia Manca, University of Liverpool

  47. R Parity Violation - d - d ~  0 1 ~ ´211 + ´211 ~ u - - - u • RPVtestedinProductionandDecayofSUSYparticles l133 l122 m+ m- • Resonant sparticle production -> l’ijk coupling • Selection: 2jets+2isolated m’s • l’211 • RPV decay of LSP(c01) -> lijk coupling • Selection: • 3 (=e,m)+ET+channel dependent cuts • l121 ->(eeee,eeem,eemm) +nn • l122 ->(mmmm,mmme,mmee) +nn Giulia Manca, University of Liverpool

  48. RPV Neutralino Decay • Model: • R-parity conserving production => two neutralinos • R-parity violating decay into leptons • One RPV couplings non-0: l122 , l121 • Final state: 4 leptons +Et • eee, eem, mme, mmm • 3rd lepton Pt>3 GeV • Largest Background: bb • Interpret: • M0=250 GeV, tanb=5 l121>0 l122>0 ~ ~ m(c+1) >165 GeV m(c+1) >181 GeV Giulia Manca, University of Liverpool

  49. R Parity Violation Limits • (L=154 pb-1) : l’211 • (L=160 pb-1) : l122 M(c0(+)1)>84(165) GeV/c2 • (L=238 pb-1) : l121M(c0(+)1)>95(181) GeV/c2 • (L=200 pb-1) : l133M(c0(+)1)>66(118) GeV/c2 tanb=2,A0=0,m<0 All improve on Run I Giulia Manca, University of Liverpool

  50. Non-collider LSP searches • DAMA, CDMS, Edelweiss,.. • Direct LSP detection through nuclear recoil • Icecube: indirect search for n from LSP annhiliation in the Sun See talk from Bergstrom at SUSY05 Giulia Manca, University of Liverpool

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