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Exploring New Physics Beyond the Standard Model at CDF

Dive into the search for new phenomena at CDF with a focus on Supersymmetry, Higgs boson, and more. Discover how SUSY can address the mysteries of dark matter, unification of forces, and mass hierarchy. Learn about particle measurements at CDF and the potential of sparticles at the Tevatron.

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Exploring New Physics Beyond the Standard Model 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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