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Searches at the Run II Tevatron Collider

Searches at the Run II Tevatron Collider. Leslie Groer on behalf of the DØ and CDF Collaborations Columbia University, New York Conference on the Intersections of Particle and Nuclear Physics New York City, NY May 22, 2003.

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Searches at the Run II Tevatron Collider

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  1. Searches at the Run II Tevatron Collider Leslie Groeron behalf of the DØ and CDF Collaborations Columbia University, New York Conference on the Intersections of Particle and Nuclear Physics New York City, NY May 22, 2003 Searches at the Run II Tevatron Collider

  2. Searching for New Phenomena at the Tevatron • Many different forms • Observation of the last unseen particle predicted by SM • Higgs • Discovery of particles not in the SM • SUSY, Leptoquarks • Identification of new gauge interactions • W’/Z’, Technicolor • Unexpected complexities beyond the SM • Compositeness • Fundamental changes to modern physics • Extra dimensions • Common theme - look for experimental signatures that could exhibit deviations from expectations • Prefer to set model independent limits Outline • Tevatron Run II • CDF+DØ Detectors • Preliminary Results • Higgs • New Physics • Run II future prospects • Conclusions Searches at the Run II Tevatron Collider

  3. Chicago  circumference: 6.2 km Booster CDF DØ Tevatron p source Main Injector + recycler - Tevatron Run II pp Collider • ’92-96 Run I 125 pb-1 • top quark discovery • ’96-’00 Accelerator and Detector upgrades • Main Injector and Recycler rings • Increased luminosity and energy • 2001-2005 Run IIa 2 fb-1 • Upgrade Silicon and Trigger • 2006 Run IIb 9-15 fb-1 Run II Delivered Luminosity Total ~ 240 pb-1 Best week: ~7 pb-1 L= 4.5 x 1031 cm-2s-1 • 1.8 TeV  1.96 TeV • e.g. tt increase ~ 30% • 6 p x 6 pbar  36 p x 36 pbar • Bunch spacing 3.5s  0.396s Searches at the Run II Tevatron Collider

  4. Major upgrades to both detectors New inner tracking chambers and silicon detectors Extensions and improvements to muon systems and triggering Complete replacement of trigger and DAQ elements for higher rate DØ: SMT, CFT, 2T superconducting solenoid, preshowers, forward muon CDF & DØ Run II Detectors CDF DØ • CDF: SVX, ISL, COT, TOF, plug calorimeters, intermediate muon Searches at the Run II Tevatron Collider

  5. Production cross section and decays are all calculable within the SM Inclusive Higgs cross section ~ 1pb gg fusion ~0.7 pb (MH = 120 GeV) (very large background) Associated production with W/ZWH ~ 0.16 pb ZH ~ 0.1 pb leptonic decays of W/Z help give the needed background rejection At higher masses, can use inclusiveproduction plus WW decays Decay channels For MH < 135 GeV, H  bb For MH > 135 GeV, HWW Associated production Hunting for the Higgs at the Tevatron Gluon fusion LEP 95% CL MH>114.4 GeV/c2 H bb H  WW H  bb H  WW b-tagging and Mbb resolution & scale are critical for a light Higgs ! Searches at the Run II Tevatron Collider

  6. L= 35 pb-1 L= 35 pb-1 Wl channel Di-jet Invariant Mass Mjj Zll channel Di-jet Invariant Mass Mjj W/Z + Jets in Leptonic Channels • Z+jets • 2 high pT lepton (ee or ) with mass consistent with Z • Jets pT > 20 GeV in || < 2.5 • First step towards W(→lv )/Z(ll) + H(bb) measurement • Major background: W/Z + di-jets • W+jets • Isolated high pT lepton (e or ) with large missing ET • Jets pT > 20 GeV in || < 2.5 Dominated by Jet energy scale systematic uncertainty Improvements • b-tags • Jet and mET resolutions • Optimize analyses 36 events ~340 events Searches at the Run II Tevatron Collider

  7. HiggsW*W/ final states • HW*Wl+l- (search for dilepton + mET) • h (search for high pT isolated diphotons) • A lot of interest in these channels as could be greatly enhanced by new couplings: • 4th generation • Fermiophobic or Topcolor Higgs • Physics backgrounds: Z/*, WW, tt, W/Z+jets, QCD • Use spin correlations to suppress background contributions in leptonic mode() • Derive .Br limits assuming BR = 1 HW*Wl+l- h Searches at the Run II Tevatron Collider

  8. CDF Searches for H++ • LR Symmetry breaking: SU(2)L x SU(2)L x U(1)B-L SU(2)L x U(1)L • Higgs fields are a left-right doublet (½,½,0) and 2 triplets: • SUSY models suggest low mass doubly-charged Higgs H++ Properties and Selection: • Pair (*/Z exchange) or singly (WW fusion) produced in pp collisions • Same sign leptons decay mode provide strong experimental signature • Inclusive electron trigger used (915.3 pb-1) • Two central same-sign electrons required • MH10% dielectron mass windows explored • Acceptance 20-35% • 0 events observed • Bckd: 0.60.5 Searches at the Run II Tevatron Collider

  9. DØ Run II Preliminary DØ ee channel L= 50.0 pb-1 CDF e +  combined L= 72 pb-1 Run I: MZ’ > 670 GeV Run II(ee): MZ’ > 650 GeV/c2 Run II(): MZ’ > 455 GeV/c2 Run I (ee): MZ’ > 690 GeV /c2 Limits on new Neutral Gauge Bosons Z’ • Neutral Gauge Bosons Z’ • Assume SM couplings • Searches in both ee and  channels • No excess observed in e or  channels • Bckds: DY, QCD misid electrons, WW, WZ, tt Searches at the Run II Tevatron Collider

  10. Searches for Large Extra Dimension • Assume SM particles are confined to a 3D-brane • Gravity propagates in the extra dimensions • Signature is an excess of high mass dilepton and diphoton events from virtual KK graviton diagrams • Angular distribution asymmetries arise from inteference terms • DØ searches in diEM and dimuon • Invariant mass • Cos * (* = scattering angle in rest frame) di-EM DØ Run II Preliminary Searches at the Run II Tevatron Collider

  11. R-S Extra Dimension Searches • Excited graviton in 5 dimensions • Kaluza-Klein Modes lead to observable spin-2 resonancesG • Free parameters: mass MG and coupling k/MPL e+m combined • Look for high mass excess in Drell-Yan dilepton events • CDF searches in ee and  channels Dielecton: MG’ > 535 GeV/c2 Dimuon: MG’ > 370 GeV/c2 Searches at the Run II Tevatron Collider

  12. / ET New Physics Searches in Diphoton Channels • Gravity Mediated SUSY • LSP is a light (<< 1 keV) gravitino, phenomenology driven by nature of the NLSP (0) • Signatures include 2 and missing ET • DØ search • Require two photons with pT > 20 GeV, apply quality and topological cuts • 0 events observed • QCD fake background determined from data (1.6  0.4) • Derive limits in Snowmass model • 95% CL on : 51 TeV gives equivalent limit on Snowmass model gives M(0) > 66 GeV • Run I limit: > 75 GeV DØ Run II Preliminary ET L= 50.0 pb-1 DØ Run II Preliminary M0 > 66 GeV/c2 Theory = "Snowmass“ slope: M = 2L, N5 = 1, tan b = 15, m > 0 Searches at the Run II Tevatron Collider

  13. Limits on New Physics in the em+X channel • Very low backgrounds → pursue analysis in a model-independent way • Require e, m pT > 15 GeV, estimate fake rates from data, physics backgrounds from simulation • 13 events, 9.6  2.7 exp. background(Z, QCD+W+jets, WWe, tt) Cross-section Limit as a function of missing ET A* snew physics (e.g. acceptance for WW→e ~ 17%) L= 33.0 pb-1 • At low MET physics backgrounds dominate, at high MET instrumental effects • Complementary search in jets + MET • Sensitivity at the 0.1 pb level already Searches at the Run II Tevatron Collider

  14. Backgrounds Data p (e ) > 15 GeV, p (e ) > 10 GeV 3216 ± 43.2 3132 T 1 T 2 10 GeV < M(ee) < 70 GeV 660.2 ± 19.1 721 M > 15 GeV 96.4 ± 8.1 123 T Add. Isolated Track, p > 5 GeV 3.2 ± 2.3 3 T Missing E > 15 GeV 0.0 ± 2.0 0 T Search in Trileptons: eel + X • Start from dielectron sample: understand trigger, reconstruction, simulation • Also verify determination of QCD fake background (from data) • Main backgrounds: Zee, and We) • .Br(3 leptons) < 3.5 pb (95% C.L.) L= 42.0 pb-1 • Typical selection efficiency for SUGRA 2-4% • Sensitivity still about factor 7 away from extending excluded area in parameter space • working on improving efficiency, adding channels Searches at the Run II Tevatron Collider

  15. New: CDF Search for Excited Electrons e* • pp  e* + e  e + e (U. Baur PRD42, 3, 1990) • Compositeness scale  • Reconstruct M(e) in ee events • Bckds: Z, Z+jet, Multijet, W+jets • No events observed in 72 pb-1 • New Limit on e* mass is 785 GeV (=Me*) • Previous limit from H1 was 223 GeV Searches at the Run II Tevatron Collider

  16. Measurements of tau leptons important for tests of the SM and in the Higgs and SUSY sectors Large backgrounds from jets Multivariate techniques useful Both experiments have established a Z    eh signal CDF has measured .B(W h) Searches in heavy flavor: tau leptons CDF Z .BR(W) = 2.62  0.07stat  0.21sys  0.16lum nb .BR(Wl) = 2.69  0.1 nb (NNLO) DØ Zeh OS-SScollinear approximation CDF Run II Preliminary L= 70 pb-1 L= 50 pb-1 14  9 data, 13  4 expected Ntracks • DØ also seen Z    h using NN techniques Searches at the Run II Tevatron Collider

  17. Extended gauge sectors and composite modelsLQ Directly couple leptons and quarks LQ  lq or q, =BR(LQlq) Search for dilepton + jets and reconstruct LQ mass- or - Search for mET and dijets Limits depend on coupling Assume =1 or 0 for limits LQ LQ LQ LQ Search for LeptoQuarks L= 40.0 pb-1 MLQ2 > 157 GeV/c2 Run I >200 GeV DØ LQ2 MLQ1 > 230 GeV/c2 Run I > 220 GeV/c2 60 < MLQ > 107 GeV/c2 CDF LQq 0 events, bckd: 3.43 42 events, bckd: 4311 Searches at the Run II Tevatron Collider

  18. Inclusive jet sample • 2 highest ET jets, ||<2 Search for Resonances in Dijets • Test QCD and sensitive to high mass resonances • Both experiments have measured dijet cross-section in Run II • Agreement so far with SM expectations • No significant excess beyond the Standard Model • Fit mass spectrum with simple background parameterization • Search for bumps comparable with the mass resolution • Derive mass limits on the BR for various exotic particles Searches at the Run II Tevatron Collider

  19. CHArged Massive stable Particles To set limits usestable stopmodel TOF • Long lived particles escape without decaying • Look like isolated slow-moving high-pT muon • Use TOF and look for t(TOF) –t (interaction) • Derive limit on production • Interpret 95% CL limits in stable stop model • M(isolated stop) > 107 GeV/c2 • M(non-isolated stop) > 96 GeV/c2 • Limits independent of details of SUSY • Previous limits from ALEPH: M > 95 GeV Searches at the Run II Tevatron Collider

  20. Conclusions Run II is well underway • We have commissioned all the detectors and have initial physics results • Cross-sections: W/Z, b-quarks, jets, B-lifetimes, rediscovered top • New phenomena and Higgs searches are underway! • Many results already competitive with Run I • Excellent performance of new tracking systems • CDF L2 Silicon displaced Vertex Trigger a great success • DØ Silicon Track Trigger online by this summer • Fully exploiting the luminosity delivered by the Tevatron • New Physics results this summer (LP03, etc) + publications • Sensitive at the 0.1 pb and 1 TeV scale in many channels • Joint working group re-evaluating the Tevatron Higgs reach • CoM Energy (~ x1.3-2), luminosity (~ x20-50), better detectors and analysis techniques (~ x2?)  ~ x100 increase in sensitivity for some channels The Tevatron will be the place for high-pT for the next few years Searches at the Run II Tevatron Collider

  21. Backups Searches at the Run II Tevatron Collider

  22. m END WALL 2.0 HADRON Time of Flight = 1.0 n CAL. 0 30 SOLENOID 1.5 = 2.0 n 1.0 COT = 3.0 n END PLUG HADRON CALORIMETER 0 3 END PLUG EM CALORIMETER .5 0 2.5 0 .5 1.0 1.5 2.0 3.0 m Inner Silicon Intermediate Silicon CDFII Detector • Retained from Run I • Solenoid (1.4 Tesla) • Central calorimeters • Central muon detectors • New in Run II • Tracking system • Silicon vertex detector (SVXII) • Intermediate silicon layers • Central outer tracker (COT) • End plug calorimeter • Intermediate muon detectors • Time of flight system • Front-end electronics • Trigger system • DAQ system Searches at the Run II Tevatron Collider

  23. DØ Inner Tracking Volume (2T) Searches at the Run II Tevatron Collider

  24. LEP excluded at 95% C.L. Tevatron Higgs Working Group • The Higgs discovery potential for Run II was evaluated(hep-ph/0010338) using a parameterized fast detector simulation • Discovery at 3-5 can be made • Combine all channels, data from both D0 and CDF • Improve understanding of signal and background processes • b-tagging, resolution of Mbb • Advanced analysis techniques are vital • Largest luminosity required to discover Higgs • Reevaluation of the expectations with real detector simulations and Run II experience underway at the moment Fermilab Run II Higgs Workshop Searches at the Run II Tevatron Collider

  25. 114 GeV 200 GeV Searching for the Higgs • Focus has been on experiments at the LEP e+e–collider at CERN (European Laboratory for Particle Physics) • Fits of electroweak data from precision measurements of parameters of the W and Z bosons, combined with Fermilab’s top quark mass measurements, set an upper limit of mH ~ 200 GeV • direct searches for Higgs production exclude mH < 114.4 GeV/c2 • Much of the favored region already excluded • Fermilab Tevatron Run II has an exciting window of opportunity before LHC turn on Searches at the Run II Tevatron Collider

  26. Tevatron Luminosity Goals: 2003 • Base • 200 pb-1 for FY03 • 10 pb-1/week by year end • Stretch • 320 pb-1 for FY03 • 15 pb-1/week by year end • FY02 • 80 pb-1 for the year • 6.7 pb-1 best week Searches at the Run II Tevatron Collider

  27. Tevatron Luminosity Scenarios Earliest date for LHC physics Searches at the Run II Tevatron Collider

  28. Expectedbb mass resolutions • Directly influences signal significance • Requires b-jet specific energy corrections (semi-leptonic, fragmentation) • Z  bb will be a calibration signal for b-jet energy corrections • To improve mass resolution, combine tracks with calorimeter cells for jet energy measurement Jet energy corrections CDF observation in Run I Z  bb Higgs simulation for 2 x 15fb-1 (2 expt’s) Z Higgs mH = 120 GeV Searches at the Run II Tevatron Collider

  29. increasing luminosity CDF Run 1 analysis (4 jets, 3 b-tags) sensitive to tan  > 60 Preliminary SUSY Higgs Production at the Tevatron • bb(h/H/A) couplings are enhanced at large tan  (= ratio of v.e.v’s) •  ~ 1 pb for tan  = 30 and mh = 130 GeV bb(h/A)  4b one expt Searches at the Run II Tevatron Collider

  30. b-tagging • b-tagging explores IP significance method • Lepton from semileptonic decay of b is very useful • Impact Parameter > 0 •  track crosses jet axis after primary vertex m + jet sample Jet Positive IP Resolution track Interaction point b enhanced • Impact Parameter < 0 • track crosses jet axis before primary vertex Jet Interaction point Significance = IP/sIP track Negative IP Searches at the Run II Tevatron Collider

  31. B-tagging • B-tagging is crucial for light Higgs search to reject light-quark content • Estimated efficiency and fake rates from impact parameter resolution • b-tag efficiency ~60% • c-quark mistag rate ~15-20% • Light quarks (u,d,s) mistag rate ~few % • Ongoing improvement in alignment and track-finding efficiency High-pTrel muon sample MC Searches at the Run II Tevatron Collider

  32. DØ Search Scorecard Searches at the Run II Tevatron Collider

  33. Run IIa Prospects • Towards the next few years: Event yields per experiment (2 fb-1) DØ / CDF Run 2a Prediction Sample W’ln Z’ll WV (W’ln, V=W,g,Z) ZV (Z’ll, V=W,g,Z) tt (mass sample, 1 b-tag) Run I 77k 10k 90 30 20 Run IIa 2300k 202k 1800 500 800 MW~40 MeV Mt ~ 3 GeV Searches at the Run II Tevatron Collider

  34. Run IIB Upgrades • Both detectors were designed to withstand ~2-4 fb-1 with an average of ~2-3 interactions per crossing • Integrated luminosity limited by radiation damage to silicon tracker • Instantaneous luminosity limited by trigger rejection • Tevatron goals for Run IIb are to accumulate5-15 fb-1 with an average of ~5 interactions per crossing, necessitating • Replacement of silicon trackers • Similar design for both and common SVX4 chip • Replacement and upgrades to few key trigger and DAQ components for high-pT physics program • Run 2 to continue in 2006 following ~7 month shutdown • All critical elements have been prototyped, sensor procurement has begun DØ CDF CDF Searches at the Run II Tevatron Collider

  35. The “Luminosity Lift” New physics panoramas open up each time we take the “Luminosity Lift”

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