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Searches for New Phenomena at CDF

Searches for New Phenomena at CDF. Introduction Supersymmetry: Higgs Squarks and Gluinos Charginos and Neutralinos Indirect search: B s  mm Non-SUSY: Dilepton Mass Spectrum Signatrure: Diphoton+X Summary and Outlook. Beate Heinemann, University of Liverpool. UCLA, March 15th 2006.

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Searches for New Phenomena at CDF

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  1. Searches for New Phenomena at CDF • Introduction • Supersymmetry: • Higgs • Squarks and Gluinos • Charginos and Neutralinos • Indirect search: Bsmm • Non-SUSY: • Dilepton Mass Spectrum • Signatrure: Diphoton+X • Summary and Outlook Beate Heinemann, University of Liverpool UCLA, March 15th 2006

  2. The Standard Model • Matter is made out of fermions: • quarks and leptons • 3 generations • Forces are carried by Bosons: • Electroweak: ,W,Z • Strong: gluons • Higgs boson: • Gives mass to particles • Not found yet H B. Heinemann

  3. What is Beyond the SM? • Many good reasons to believe there is as yet unknown physics beyond the SM • Many possible new particles/theories: • Supersymmetry: • Many flavours • Extra dimensions (G) • New gauge groups (Z’, W’,…) • New fermions (e*, t’, b’, …) • Leptoquarks • Can show up! • As subtle deviations in precision measurements • In direct searches for new particles B. Heinemann

  4. There is a Lot Unknown The Standard Model • only accounts for 4% of matter in Universe • No candidate for Cold Dark Matter(≈25%) • cannot explain large mass hierarchy in fermion sector: • >10 orders of magnitude • does not allow grand unification: • electroweak and strong interactions do not unify • has large radiative corrections in Higgs sector • require fine-tuning of parameters • Cannot explain matter-antimatter asymmetry? Supersymmetry can solve three of these problems Hubble Constant Matter Density SM B. Heinemann

  5. What’s Nice about Susy? With SUSY • Unifications of forces possible • Dark matter candidate exists: • The lightest neutral gaugino • Radiative corrections to Higgs acquire SUSY corrections: • No fine-tuning required • Changes relationship between mW, mtop and mH: • Also consistent with precision measurements of MW and mtop B. Heinemann

  6. CDF and the Tevatron B. Heinemann

  7. Tevatron Run II _ • World’s highest energy collider • Tevatron Accelerator: • Integrated luminosity >1.5 fb-1 by now: • CDF data taking efficiency about 83% • Integrate Ldt=4-8 fb-1 by 2009 p p Key parameter: N= • Ldt Delivered: 1.6 fb-1 Recorded: 1.3 fb-1 B. Heinemann

  8. Tevatron Luminosity B. Heinemann

  9. Measurement of Final State Objects with CDF Measurement of Final State Objects with CDF MUON CHAMBERS h = 1.0 CENTRAL HAD CALORIMETER END WALL HAD CAL. CENTRAL EM CALORIMETER SOLENOID h = 2.0 h = 3.0 Silicon Vertex Detector CLC PLUG HAD CAL. PLUG EM CAL. CENTRAL OUTER TRACKER B. Heinemann

  10. Measurement of Final State Objects with CDF Measurement of Final State Objects with CDF • Electron ID : • Coverage : |h|<3.6 • |h|<2 (w/ trk) • ID eff. ~ 80-90% • Photon ID : • Coverage : |h|<2.8 • ID eff. ~ 80% B. Heinemann

  11. Measurement of Final State Objects with CDF Measurement of Final State Objects with CDF • Muon ID : • Coverage : |h|<1 • ID eff. ~ 90-100% B. Heinemann

  12. Measurement of Final State Objects with CDF Measurement of Final State Objects with CDF th ID t cone isolation • Tau ID : • Narrow iso. cluster • Low # tracks • p0 identification • Coverage : |h|<1 • ID eff. ~ 46% B. Heinemann

  13. Measurement of Final State Objects with CDF b do Lxy y z x • Jet ID : • Cluster of CAL towers • Coverage : |h|<3.6 • Heavy Flavor Jet Tagging : • Id HF jets via semi-leptonic decay • Find soft lepton in jets • Coverage : |h|<1 • Id HF jets via finding displaced vertex • Coverage : |h|<1.5 B. Heinemann

  14. Supersymmetry B. Heinemann

  15. Supersymmetry g ~ G G • SM particles have supersymmetric partners: • Differ by 1/2 unit in spin • Sfermions (squarks, selectron, smuon, ...): spin 0 • gauginos (chargino, neutralino, gluino,…): spin 1/2 • No SUSY particles found as yet: • SUSY must be broken: breaking mechanism determines phenomenology • More than 100 parameters even in “minimal” models! B. Heinemann

  16. Sparticle Cross Sections: Tevatron Cross Section (pb) 150 events produced so far (1.5 fb-1) T. Plehn, PROSPINO B. Heinemann

  17. Sparticle Cross Sections:LHC Cross Section (pb) 100 events with 1 fb-1 T. Plehn, PROSPINO B. Heinemann

  18. Sparticle Cross Sections:LHC 100 events with 1 pb-1 Cross Section (pb) 100 events with 1 fb-1 T. Plehn, PROSPINO B. Heinemann

  19. Higgs in the MSSM • Minimal Supersymmetric Standard Model: • 2 Higgs-Fields: Parameter tanb=<Hu>/<Hd> • 5 Higgs bosons: h, H, A, H± • Neutral Higgs Boson: • Pseudoscalar A • Scalar H, h • Lightest Higgs (h) very similar to SM • At high tanß: • A is degenerate in mass with either h or H • Decay into either tt or bb for mA<300 GeV: • BR(A tt) ≈ 10%, BR(A bb) ≈ 90% • Cross section enhanced with tan2 • C. Balazs, J.L.Diaz-Cruz, H.J.He, T.Tait and C.P. Yuan, PRD 59, 055016 (1999) • M.Carena, S.Mrenna and C.Wagner, PRD 60, 075010 (1999) • M.Carena, S.Mrenna and C.Wagner, PRD 62, 055008 (2000) B. Heinemann

  20. Neutral MSSM Higgs • Production mechanisms: • bb  A/h/H • gg  A/h/H • Experimentally: • pp b+X  bbb+X • pp +X tt +X B. Heinemann

  21. MSSM Higgs: Tau-Selection • Select t t Events: • One t decays to e or m • One t decays to hadrons • Require: • e or m with pT>10 GeV • Hadronic t: • Narrow Jet with low multiplicity • 1 or 3 tracks in 10o cone • No tracks between 10o and 30o: • Cone size descreasing with increasing energy • Low p0 multiplicity • Mass<1.8 GeV • Kinematic cuts against background: • W+jets • Photon+jets • Dijets B. Heinemann

  22. Acceptance and Background • Main background: • Drell-Yan tt • Indistinguishable signature => Separate kinematically • No full mass reconstruction possible for low Higgs pT: • Form mass like quantity: mvis=m(t,e/m,ET) • Good separation between signal and background • Data mass distribution agrees with SM expectation: • mvis>120 GeV: • 8.4±0.9 expected, 11 observed B. Heinemann

  23. MSSM Higgs: Results • CDF pp  A+Xtt+X • Sensitivity at high tanb • Exploting regime beyond LEP • Brandnew result from DØ • Combined with other mode • pp  bA+Xbbb+X • Future (L=8 fb-1): • Probe values down to 25-30! B. Heinemann

  24. ~ ~ 3rd generation Squarks • 3rd generation is special: • Masses of one can be very low due to large SM mass • Particularly at high tan • Direct production or from gluino decays: • pp bb or tt • pp gg bbbb or tttt • Decay of sbottom and stop: • b b0 • Stop depends on mass: • Heavy: t t0 • Medium: t b± bW0 • Light: t c0 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ B. Heinemann

  25. Bottom Squarks • This analysis: • Gluino rather light: 200-300 GeV • BR(g->bb)=100% assumed • Spectacular signature: • 4 b-quarks + ET • Require b-jets and ET>80 GeV ~ ~ Expect:2.6±0.7 Observe: 4 Exclude new parameter space in gluino vs. sbottom mass plane B. Heinemann

  26. Light Stop-Quark: Motivation • If stop quark is light: • decay only via t->cc10 • E.g. consistent with relic density from WMAP data • Balazs, Carena, Wagner: hep-ph/0403224 • WCDM=0.11+-0.02 • m(t)-m(c10)≈15-30 GeV/c2 • m(t)<165 GeV/c2 • Search for 2 charm-jets and large Et: • ET(jet)>35, 25 GeV • ET>55 GeV ~ ~ ~ ~ ~ B. Heinemann

  27. Light Stop-Quark: Result • Charm jets: • Use “jet probability” to tag charm: • Probability of tracks originating from primary vertex • Improves signal to background ratio: • Signal Efficiency: 30% • Background rejection: 92% • Data consistent with background estimate • Observed: 11 • Expected: 8.3+2.3-1.7 • Main background: • Z+ jj -> vvjj • W+jj -> tvjj B. Heinemann

  28. Stop Quark: Result and Future • Due to slight excess in data: • No limit set on stop quark mass yet • Future light stop reach : • L=1 fb-1: m(t)<160 GeV/c2 • L=4 fb-1: m(t)<180 GeV/c2 • LHC: • Direct production will be tough to trigger • But gluino decay to stop and top yields striking signature! • Two W’s, two b-quarks, two c-quarks and missing ET • If m(g)>m(t)+m(t) ~ ~ ~ ~ B. Heinemann ~ ~ ~ ~ ~ ~ ~ ~

  29. Charginos and Neutralinos Et Et Et • Charginos and Neutralionos: • SUSY partners of W, Z, photon, Higgs • Mixed states of those • Signature: • 3 leptons + • Recent analyses of EWK precision data: • J. Ellis, S. Heinemeyer, K. Olive, G. Weiglein: • hep-ph/0411216 • Light SUSY preferred ~ B. Heinemann

  30. 3 leptons + Et • Many analyses to cover full phase space: • Low tan: • 2e+e/m • 2m+e/m • me+e/m • High tan: • 2e+isolated track • Sensitive to one-prong tau-decay • Other requirements: • Dilepton mass >15 GeV and not within Z mass range • Less than 2 jets • Significant ET B. Heinemann

  31. Trileptons: Result Still no SUSY! Will need to set limit B. Heinemann

  32. 3-muon Event MET CMUP CMIO CMX B. Heinemann

  33. Rare Decay: Bsm+m- • SM rate heavily suppressed: • SUSY rate may be enhanced: • Related to Dark Matter cross section (in one of 3 cosmologically interesting regions) • Recently gained a lot of attention in WMAP data SUSY analyses, see e.g. • B. Allanach, C. Lester: hep/ph-0507383 • J. Ellis et al., hep-ph/0504196 • S. Baek, Y.G.Kim, P. Ko, hep-ph/0406033 • R. Dermisek et al.,hep-ph/0507233 (Buchalla & Buras, Misiak & Urban) (Babu, Kolda: hep-ph/9909476+ many more) S. Baek, Y.G.Kim, P. Ko, hep-ph/0406033 B. Heinemann

  34. Bsm+m- vs. Trileptons 1x10-7 Trileptons: 2fb-1 A.Dedes, S. Mrenna, U. Nierste, P. Richardson hep-ph/0507233 B. Heinemann

  35. Indirect Search: Bs->mm • Preselection: • Two muons with pT>1.5 GeV/c • Dimuon vertex displaced from primary • Identify variables that separate signal from background: • Decay length:  • Points towards primary vertex • Isolated from other tracks • Construct likelihood of variables: • Excellent separation • Cut at likelihood ratio >0.99 B. Heinemann

  36. Bs->mm :Result and Future • Result: • 0 events observed • Backgrounds: • 0.81± 0.12 for (CMU-CMU) • 0.66 ± 0.13 for (CMU-CMX) • Branching Ratio: • CDF: • BR(Bs->mm)<1.5 x 10-7 at 90%C.L. • Combined with D0: • BR(Bs->mm)<1.2 x 10-7 at 90%C.L. • Future: • Probe values of 2x10-8 B. Heinemann

  37. Impact of Bsm+m- limits: Now A.Dedes, S. Mrenna, U. Nierste, P. Richardson hep-ph/0507233 S. Baek, Y.G.Kim, P. Ko, hep-ph/0406033 • Starting to constrain MSSM parameter space B. Heinemann

  38. Impact of Bsm+m- limits: L=8 fb-1 A.Dedes, S. Mrenna, U. Nierste, P. Richardson hep-ph/0507233 S. Baek, Y.G.Kim, P. Ko, hep-ph/0406033 • Tevatron will severely constrain parameter space B. Heinemann

  39. Impact of Bsm+m- limits: LHC A.Dedes, S. Mrenna, U. Nierste, P. Richardson hep-ph/0507233 S. Baek, Y.G.Kim, P. Ko, hep-ph/0406033 • LHC will probe SM value with about 100 fb-1 B. Heinemann

  40. Non-Susy Searches

  41. High Mass Dileptons Standard Model high mass dilepton production: New physics at high mass: • Resonance signature: • Spin-1: Z’, W’ • Spin-2: Randall-Sundrum (RS) Graviton • Spin-0: Higgs, Sneutrino • Tail Enhancement: • Contact Interactions • Large Extra Dimension (Arkhani-Hamed, Dimopoulos, Dvali) B. Heinemann

  42. Z´ee Search • Dielectron mass spectrum and angular distribution: • 2D analysis improves sensitivity • Data agree well with Standard Model spectrum • No evidence for mass peak B. Heinemann

  43. Z´ee Signal Examples • Angular distribution has different sensitivity for different Z’ models B. Heinemann

  44. Limits on New Physics • Mass peak search: • Tail enhancement: contact interaction B. Heinemann

  45. Signature Based Searches • All searches cover unique signatures, e.g.: • Three lepton and missing ET • B- or c-jets and missing ET • 2 b--jets or c-jets and missing ET • Dilepton invariant mass • However, can also search really model independent to make sure we don’t miss anything! • Diphoton+X B. Heinemann

  46. Signature: Diphoton+X • Search for any objects produced in association with 2 photons • Electron, muon, tau • Photon • Jet • Missing ET • Data consistent with background prediction =e,m,g B. Heinemann

  47. Diphoton+X: Invariant Mass • Kinematic distributions also agree well with background prediction • Triphoton analysis first physics result with >1 fb-1 of data! B. Heinemann

  48. Summary and Outlook more than 1 fb-1! • CDF and Tevatron running great! • Most analyses based on up to 350-750 pb-1 • Will analyze 1 fb-1by summer 2006 • Anticipate 4.4-8.6 fb-1 by 2009 • Searches probe Nature in new, unique way • Tevatron most powerful tool today: • provide world’s best constraints on nearly anything that is being searched for • LHC will be very powerful in the future • It is an exciting time B. Heinemann

  49. Backup Slides

  50. Dirac Magnetic Monopole • Bends in the wrong plane( high pt) • Large ionization in scint (>500 Mips!) • Large dE/dx in drift chamber TOF trigger designed specifically for monopole search mmonopole > 350 GeV/c2 B. Heinemann

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