1. Searches for New Physics with CDF Else Lytken, Purdue University

2. Else Lytken, March 30, 20062 Outline o Introduction to the Tevatron and CDF o CDF search strategies o Selection of results: o Higgs searches o SUSY searches o Other searches: bump hunting, model-independent o Conclusions

3. Else Lytken, March 30, 20063 The Tevatron p-p collider located at Fermilab ~ 50 miles from Chicago Run II started in Spring 2001 anti-protons: electron cooling accumulation: up to 20 mA/hour Routine operation of storage rings Beams collide every 396 ns with  s = 1.96 TeV Current luminosity record: 1.8*10 32 cm -2 s -1 26.1 pb -1 in a week Plan: Take data until 2009, collecting a total of 4-8 fb -1 by end of Run II _ 2km 1mA ~ 10 10 p _ ^

4. Else Lytken, March 30, 20064 Collider Detector @ Fermilab Had Calorimeter Muon system Drift chamber Em Calorimeter  =0  =1 Inner tracker (Si) Towers 15 0 (  ) x 0.1(  ) Central:  /E = 13.5%/  E T Extends to |  |~3.8  /E = 0.5/  E coverage:|  |< 1.2 Hit res: 140 microns coverage: |  |~2.0 IP res: 40 microns Basic coverage |  |<1.0 Extension: |  |<1.5 B field: 1.4 T

5. Else Lytken, March 30, 20065 Performance Run II now mature environment  stable operation of accelerator and detectors More than 1fb -1 of data on tape Analyses shown here use up to 1fb -1 (< when corrected for running conditions) 10  Run I dataset! 1fb -1

6. Else Lytken, March 30, 20066 Leptons and jets All searches highly dependent on efficient and reliable object identification Typical efficiencies : (Jet fake rate ~ 10 -3 - 10 -4 ) ~ 45% at high p T Calorimeter towers: Coverage : |  |<3.6 Heavy flavour jets (|  |<1.5) : Identified by tagging soft leptons or secondary vertex. e  Eff:80-90%~ 80%85-95%~50% Coverage |  |<2|  |<2.8|  |<1.5|  |<1

7. Else Lytken, March 30, 20067 New Physics The standard model has been a great success Too many questions blowing in the wind: hierarchy problem, divergences at high E, how to explain dark matter, etc.  Something else is out there to take over at higher energies.  Tevatron is currently the place to search for new high pt physics! Some of the focus points for CDF searches: SM and Extended higgs sector Supersymmetry Extra dimensions (large or universal) New heavy gauge bosons Compositeness Generic signature-based searches – always preparing for the unexpected! Very extensive program, please check out http://www-cdf.fnal.gov/physics/exotic/exotic.htmlhttp://www-cdf.fnal.gov/physics/exotic/exotic.html for more results

8. Else Lytken, March 30, 20068 NEW PHYSICS Large Missing Energy Multi-Leptons Heavy Flavor Jets Multi-Photons Long Lived Massive Particles (E T, or MET) / New resonances What we look for

9. Else Lytken, March 30, 20069 Expecting small excesses above SM + many studies have to rely on predictions from simulation to test standard model prediction  very sensitive to little imperfections (detector material distribution, tracking resolution, etc.) Now 2-3 interactions/bunch crossing, and increasing with increasing Tevatron L σ(W→lν) σ(tt) m t =175 GeV Challenges for New Physics  most analyses unbiased searches: Signal regions not looked at until confident in background estimates

10. Else Lytken, March 30, 200610 Standard Model Higgs - Higgs is only missing SM particle needed to gives masses to W, Z, fermions - Higgs-like object necessary for most beyond-SM theories. Direct bound from LEP2: m H >114.4 GeV Indirect from precision EWK fits: m H <175 GeV (<207 GeV if low mass area excl ) Preferred higgs mass (89 GeV) already excluded Includes new top mass from TeV: m top = 172.5±2.3GeV

11. Else Lytken, March 30, 200611 Higgs Searches @ TeVatron Tevatron strategy: Low higgs masses: (<135 GeV) Associated higgs production WH, ZH, with H  bb (single higgs dominated by dijet background) Cross section is few hundred fb -1 and efficiencies a few %  Very challenging For m Higgs >135 GeV: gg  H with H  WW* cross section (pb) SM Higgs cross section (HIGLU,V2HV) pp,  s=1.96 TeV -

12. Else Lytken, March 30, 200612 WH  l bb Search for resonant mass peak in dijets 1 tag: 175±26 expected, 187 observed 2 tags: 15 ±3 expected, 14 observed Same final state also used to set limit for techni-  given mass of techni-  Among best channels for low mass higgs 1 high p T lepton (e or µ) MET > 20 GeV 2 b jets ( at least 1 tagged) Main background: Wbb, Wcc, top

13. Else Lytken, March 30, 200613 Light flavor mistags QCD Top EWK ZH  bb MET=145 GeV, dijet mass: 82 GeV In mass window 80-120 GeV: SM prediction: 4.36  1.02 events Observe: 6 events. Background composition: QCD normalized in control region: Jet E T = 100 GeV, tagged Jet E T = 55 GeV tagged Select events with 2 jets (at least 1b-tag) Missing Et >70 GeV Candidate event:

14. Else Lytken, March 30, 200614 H  WW* Spin 0 higgs: spin of W’s from H back-to-back  leptons have small angular separation and small inv mass W+W+ e+e+ W-W- e-e- n Look for opp sign dileptons + MET>25 GeV Veto Z mass window Main bkg: direct WW production

15. Else Lytken, March 30, 200615 H  WW* results Suppress background: Mass cut, M ll <½M H and fit to  No excess observed, overall see 14 events as expected ee ee ll Total bkg 4.5±0.46.6±0.62.9±0.314.0±1.3 H  WW 0.11±0.010.23±0.010.11±0.010.44±0.03 Obs45514 150 GeV Higgs

16. Else Lytken, March 30, 200616 Higgs Searches: CDF Combined Results In addition to more data: Several improvements underway to bridge the gap

17. Else Lytken, March 30, 200617 Supersymmetry Idea: extend SM with symmetry fermions  bosons If realized, lots of new particles to be found! Many attractions: Low scale supersymmetry protects higgs mass, provides dark matter candidate, unification @10 16 GeV, and consistent with precision top mass fits Spin 0 1/2 13/22 5 higgses leptonsgauge gravitino graviton h 0 /h 0,H 0,A, H ± quarks bosons GG sleptons l gluino g squarks q gauginos  ±  0 ~ ~ ~ ~ ~ ~

18. Else Lytken, March 30, 200618 SUSY@TeVatron Large selection of SUSY models and parameters Most interpretations use minimal models with tan  = v u /v d, m 0 = scalar mass, m 1/2 = fermion mass Non-exluded cross sections small Compared to LHC expectations: Tevatron LHC

19. Else Lytken, March 30, 200619 SUSY signatures SUSY searches attractive from experimental point of view due to variety of signatures: - Missing transverse energy from stable LSP’s (when R-parity conserved) - multijets from cascade decays - multileptons Lightest Susy Particle New quantum number often assumed conserved +1 SM - 1 SUSY

20. Else Lytken, March 30, 200620 MET + 3 leptons Expected signature from chargino-neutralino production Heavily constrained by LEP: m(   ) >103 GeV W* Z* Clean signature very attractive for Tevatron, Main backgrounds: DY+fake lepton/conversion, W(Z/  *) CDF takes advantage of all lepton triggers for maximum sensitivity 1 ’

21. Else Lytken, March 30, 200621 3 leptons: continued All observations in agreement with SM predictions Channel Example signal SM expected Obs µµ/e +l (0.7 fb -1 ) 2.3±0.31.2±0.2 1 ee+l (0.35 fb -1 ) 0.5±0.060.2±0.050 µµ+l (low pt) (0.3 fb -1 ) 0.2±0.030.1±0.03 0 ee+trk (0.6 fb -1 ) 0.7±0.030.5±0.1 1 Stay tuned for updated limits! (enhanced sensitivity to  ’s)

22. Else Lytken, March 30, 200622 Like-sign dileptons (704 pb -1 ) Signature for   leptons, decays of gluinos or other majorana particles  leptons Most problematic background: untagged conversions, Drell-Yan+  and W+  MET>15 GeV to suppress DY Opp sign leptonsLike-sign from conversions

23. Else Lytken, March 30, 200623 like-sign results CategoryObsPredicted  signal ee42.6 ± 0.40.64 eμeμ53.5 ± 0.61.64 µμ00.7 ± 0.10.91 Total96.8 ± 1.03.19 Interesting excess at high p T - number of events consistent with background prediction. Look forward to add more data!

24. Else Lytken, March 30, 200624 R P : 4 leptons (350 pb -1 ) Assume prompt decay of LSP  4 leptons from  decays Analysis also looked at 3 leptons ~~ Yukawa term: ijk L i L j E k Analysis accepts e and µ Sensitive to 121 and 122 _ Trilepton control regions Striking signature, virtually no SM background No cut on MET or N jets 4 Leptons: Expects 1.5±0.2 signal, <0.01 SM, observes 0  Comb. 121  0:  < 0.21 pb limits 122  0 :  < 0.11 pb / :

25. Else Lytken, March 30, 200625 MET + jets: squark and gluino Generic squarks and gluinos strongly produced Cross section @ Tevatron: ~ a few pb Expect cascade decays Signature: lots of MET and  2 jets Req.  3 jets and MET>165 GeV Bkg dominated by Z  + jets Check: compare data and QCD MC in jet domimated region SM wins again: Expect 4.1  0.6 events, observe 3

26. Else Lytken, March 30, 200626 Search for Stop Production of 3rd generation sparticles could give us first hints of SUSY: Due to larger masses of SM partners, mass eigenstates of left- and right- stops can have large mass splitting.  lightest stop, t 1, lighter than other squarks CDF looking into several possible decay modes: t 1  c  t 1  bl  R P modes: t 1  b  New result also using H T : mass(LQ3)  368 GeV Exclusion also applies to 3 rd generation LQ / ~ ~ ~ ~ ~ ~ 0101 0101 Updating!

27. Else Lytken, March 30, 200627 Indirect constraint: B S  CDF also looks at B d  Background estimation: linear extrapolation from sidebands Normalizing using B +  -  + K + Rare decay, BR in SM is ~10 -9 Loop diagrams with sparticles (or direct decay if RPV) enhance BR orders of magnitude Complementary to other SUSY e and µ searches Important at high tan 

28. Else Lytken, March 30, 200628 B S  : Results Previous limit: hep-ph/0507233 Compatible with SM backgrounds: B s Expect: 0.88±0.30 Observe: 1 B d Expect: 1.86±0.34 Observe: 2 Pink regions are excluded by either theory or experiments Green region is the WMAP preferred region Blue dashed line is the Br(Bs   ) contour Light blue region excluded by old analysis Limits with 780 pb -1 : Br(B s   )<1.0×10 -7 @ 95%CL Br(B d   )<3.0×10 -8 @ 95%CL SUSY with minimal SO(10) NEW limit:

29. Else Lytken, March 30, 200629 MSSM Higgs(es) Analysis look for:   l + hadrons For m  120 GeV: expect 8.4, observe 11 events All higgs searches working on updates for Summer 5 higgses to look for: h, H, A, H ± Charged: CDF looks for t  H ± b Neutral: enhanced production at large tan  with h/H/A  hep-ex/0508051

30. Else Lytken, March 30, 200630 Bump hunting: Z’ Several BSM models predict new heavy gauge bosons CDF searches for Z’ and W’ New result: Z’  e + e - using 819 pb -1

31. Else Lytken, March 30, 200631 Result: No signifiant bumps Lowest probability observed occurred in 52% of pseudo experiments Highest mass event: M ee = 491 GeV/c² ! exclude M Z' <850 GeV SM-Z' Scan mass spectrum: 1 GeV steps For each point: get P(bkg fluctuate  data) in mass window given by calorimeter resolution

32. Else Lytken, March 30, 200632 Large Extra Dimensions SM backgrounds: Z+ jets, with Z , W+jets, QCD Compactified extra dimensions (ADD model) with eff Planck scale M D : M² Planck ~ R n M D ² +n Search for direct production of gravitons in gG or qG final states Signature would be mono-jet + MET E T >150 Expect 265±30 events Obs: 263 MET>120 MET

33. Else Lytken, March 30, 200633 First look for anomously production of dilepton+X events (where X = large MET, jets, leptons, etc) Can be signature for many models: Extra-D, SUSY,... Analysis investigating heavy quark model 3 heavy, down-type quarks Q i, decay to Z/H/W Final state looks at lot like tt Signal region: eµ + H T >400 GeV, 2 jets >50 GeV Event expectation SM: 0.8, QQ: 0.5, observe 0 Limit:  (Q)<0.289 pb for m(Q)=300 GeV Searching for heavy objects Bjorken, Pakvasa, Tuan: hep-ph/0206116 H T = E T (e) + p T (µ) + E T (jets) + MET No overflows -

34. Else Lytken, March 30, 200634 Now looking for X  Z where X = Z’, heavy q, neutralino... Signature would be high p T excess of events in Z mass window (66  M ll  116 GeV/c²) No observed excess on high p T tail for ee or µµ More limits on heavy quarks:  (Q) <0.17 pb @ 95% CL m(Q) = 300 GeV and more to come... CDF Run II Preliminary (305 pb -1 )

35. Else Lytken, March 30, 200635 Diphoton + e/  /  Several models predict diphoton signatures: Gauge mediated SUSY models, excited leptons, fermiphobic higgs,... Analysis inspired by Run I ee  +MET event.  searches have huge backgrounds After requiring X almost no backgrounds  Do not have to optimize analysis cuts to particular model CDF has results on  +e/µ and  More analyses with  +X on the way Phys.Rev.D59.09002 (1999) by Toback et al. ~ q’

36. Else Lytken, March 30, 200636  with 1020 pb -1 All photons pass same ID cuts Background: fakes + real triphotons Expectation: 1.9 events, observe 4 No significant excess is observed Results will set limits for several models First case:  l with 683 pb -1 Background: fakes or W  / Z  Expectation: 5.0 events, observe 2  (E T ) > 13 GeV

37. Else Lytken, March 30, 200637 LEP excluded Conclusion - CDF and the Tevatron are in great shape! - Results are pouring in, many more in the pipeline - No sign of the New Physics yet More analyses and more data for Summer could take us from great limits to great discovery(ies)! Higgs sensitivity for Run II: 8 fb -1 : exclude Higgs up to mass of 135 GeV 4 fb -1 : exclude Higgs up to ~125 GeV

38. Else Lytken, March 30, 200638 We know it is out there !

39. Backup

40. Else Lytken, March 30, 200640 Vector Leptoquarks (322 pb -1 ) Assuming 3rd gen VLQ decays to b+  - signature: lepton+MET+  h +di-jet Cut on: H T =p T (l)+p T (tau)+p T (jets)+MET > 400 GeV/c New limit: mass  368 GeV/c 2 assuming Br(VLQ3  b) = 100%.

41. Else Lytken, March 30, 200641 Look in the Bs and Bd Signal Window L R > 0.99 CMU-CMU Channel: Expect Observed Prob B s 0.88±0.30 1 67% B d 1.86±0.34 2 63% CMU-CMX Channel: Expect Observed Prob B s 0.39±0.21 0 68% B d 0.59±0.21 0 55%

42. Else Lytken, March 30, 200642 High pt Z’s

43. Else Lytken, March 30, 200643 High mass ee event run: 202771, event: 8309309 central-central M ee = 491 GeV/c 2

44. Else Lytken, March 30, 200644 More Z’ Other analysis also exploring angular information:  Z’ would interfere with Z/   look for change in expected shape of cos(  *) for M ee > 200 GeV. Observation: 120 events, 115±19 expected  similar mass limit with 450 pb -1 Testing angular shape hep-ex/0602045 angle(incomming quarks, electrons) cos(  *) in Colling-Soper frame minimize ambiguity in incomming q Pt

45. Else Lytken, March 30, 200645 New top mass and the MSSM Plot from: http://quark.phy.bnl.gov/~heinemey/uni/plots/

46. Else Lytken, March 30, 200646 More on MSSM higgs Br(  bb)~90% gg,bb  bb: need to overcome large QCD BG Br(  )~10% gg,bb   overcome much smaller SM BG Projection:

47. Else Lytken, March 30, 200647 More plots from LS

48. Else Lytken, March 30, 200648 CDF Trigger System Rate of incoming events: – Every 396 ns Design specs: maximum rate of accepting events: – L1: 50 kHz – L2: 300 Hz – L3: 30 Hz L2 currently is the bottleneck – Exceeded design specs to operate at 380 Hz

49. Else Lytken, March 30, 200649 Shutdown 2006 Detectors: Various maintenance and repairs + CDF: Final Run II b upgrades: New TDC’s, upgrades to track triggers and hardware event builder. D0: Add innermost Si layer + upgrades to track and calorimeter triggers We are currently in a long showdown for maintenance of TeV Expected duration: March- June Plenty of time On track Potentially tricky

50. Else Lytken, March 30, 200650 Tagging B-jets Tagging jets with the SecVtx algorithm is a powerful way of selecting b-jets Jet is tagged: decay length L xy /  Lxy > 7 L xy >0 identifies real heavy flavor jet Tagged jet Prim. vertex 2 nd vertex L xy >0 Currently using the tight tagger Development of a “forward b-jet tagging” is in progress to increase acceptance Mistag rate is ~1% –Double-sided silicon microstrips: 800k channels! –r ~1.5 cm out to ~50 cm

51. Else Lytken, March 30, 200651 Jet reconstruction Final state partons are revealed through collimated flows of hadrons called jets Need to have common and unambiguous definition used for theory and experiments.  Jet reconstruction algorithms: - infrared and collinear safe - jet direction = parent parton direction Two main types of jet algorithms: - Cone Algorithm  JETCLU (Run I like) and MIDPOINT - K T algorithm Measurements  at hadron level Theory prediction  parton level

52. Else Lytken, March 30, 200652 Conversion removal SF

53. Else Lytken, March 30, 200653 COT Aging - Fully Recovered – Aging due to hydrocarbons coating sense wires – Fixed by adding Oxygen – Fully recovered May 2004 – 99.7% working! Silicon detector lifetime is a complex issue involving ~93% powered; ~84% working + 4% recoverable in offline Secondary vertex trigger requires 4 layers: 21 out of 24 wedges COT Gain vs. Time Jan.2002 Aug.2005 May 2004 Lifetime 0 10 fb -1 20 fb -1 30 fb -1 40 Predicted Silicon Lifetime 8 fb -1

54. Else Lytken, March 30, 200654 Electron Cooling Recycler: 3.3 km in circumference Store antiprotons at 8 GeV Mix pbars with 4.3 GeV electron beam reduce longitudinal emittance (Coulomb scattering until thermal equilibrium)

55. Else Lytken, March 30, 200655 Higgs limit from D0

56. Else Lytken, March 30, 200656 R p (R-parity) conserving – Lightest Supersymmetric Particle (LSP) is stable, escapes detector (undetected) – Results in large E T Miss striking exp. Signature (R p violating signatures) – Often include lepton flavor violating decays Breaking Models: mSugra: supergravity-inspired – Best-studied model, 5 parameters GMSB-motivated signatures – LSP: Gravitino, various next-LSP (NLSP) Experimentally: photons! Run 1 CDF e  E T Miss AMSB-motivated signatures – Long-lived particles, soft pions – Very hard at hadron colliders Lightest squark:

57. Else Lytken, March 30, 200657 e +, p T = 41 GeV MET, 45 GeV CDF Trilepton events CMIO MET CMUP CMX Mass OS141.6 GeV Mass OS227.0 GeV Jet E T = 50 GeV p T = 4 GeV e -, p T = 12 GeV

58. Else Lytken, March 30, 200658