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Exploring New Phenomena at CDF

Exploring New Phenomena at CDF

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Exploring New Phenomena at CDF

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  1. Exploring New Phenomena at CDF Jane Nachtman (Fermilab) for the CDF collaboration Exploring New Phenomena workshop

  2. Objective • This workshop is about bringing theorists and experimentalists together to focus on maximizing the Tevatron’s discovery potential • The experimental talks will briefly summarize searches for new physics at CDF and D0 • To help us think about what is possible and where we should go from here • Looking for theorists’ input! • We split the signatures • CDF – photons, jets + MET, hi-pt dileptons • D0 – leptons+jets, multi-leptons, long-lived signatures Exploring New Phenomena workshop

  3. Overview of my talk • Brief CDF and Tevatron intro • CDF searches • Signature-based, then applied to models • Photons • Applied to GMSB, Extra Dimensions • Hi-pt dileptons • Z’, G • MET+jet(s) • SUSY, LED • Global, signature-based search of all CDF hi-pt data (Vista+Sleuth) Exploring New Phenomena workshop

  4. 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 CDF Detector Exploring New Phenomena workshop

  5. Tevatron The Tevatron’s performance is better than ever!! Almost 2 fb-1 delivered, ~1.6 fb-1 recorded ( 0.95 – 1.2 fb-1 for analysis, depending on which subsystems are used) 4-8 fb-1 by 2009 Exploring New Phenomena workshop

  6. Signature-based searches at CDF • Philosophy – models come and go, but the data should stand on its own • Design “simple” searches • No optimization for models  no sophisticated cuts • Attempt to provide general result for theoretical input • Basic result : N expected from SM, N observed • Study kinematic distributions • Publish acceptance functions – plug in your own model • Drawback – may not provide maximal sensitivity to a particular model • But may point us in the right direction to look further Exploring New Phenomena workshop

  7. Signature-based searches for photon+X • Inspired by Run I hints • “eeggMET” event • Excess in lepton+photon+MET (16 obs, 7.6 +/- 0.7 exp) • Theoretical models suggest these signatures (eg GMSB) • Mix-n-match: photons, leptons (e,m,t), MET, jets,b-jets Exploring New Phenomena workshop

  8. Search for photon+lepton+X • 2 channels • Photon + lepton(e,m) + MET • Photon + lepton + lepton + X • Look for high-pt leptons, photons, high MET (reduce fakes, SM backgrounds) • In 930 pb-1 of data e+MET +MET l+MET SM 948 547 14813 Data 96 67 163 ee+X +X ll+X SM 395 263 658 Data 53 21 74 SM is W/Z gamma, W+fake No events with extra photons, leptons observed SM is W/Z gamma, W+fake No events with extra photons, leptons,MET observed No em Exploring New Phenomena workshop

  9. Check kinematics in l+gamma+MET Exploring New Phenomena workshop

  10. Diphoton + X searches • X = e,m,g,MET • Backgrounds evaluated from data • Use sidebands – loose photons not passing signal photon selection • Dataset = 1 – 1.2 fb-1 gg+X, X= SM Nobs e 3.8 +/- 0.5 1 m 0.7 +/- 0.1 0 MET 116 +/- 24 126 g 2.2 +/- 0.7 4 Exploring New Phenomena workshop

  11. Kinematics in +X channels Control region Signal region Exploring New Phenomena workshop

  12. High-mass diphotons • high ET (>15) isolated diphoton resonance • Background : QCD diphotons (simulation), jets (from data) Exploring New Phenomena workshop

  13. Long-lived Exotic particles • D0 talk will cover more in detail, just one photon-based search here • Several models predict long-lived particles: charged or neutral, decaying inside or outside detector • Charged – look like slow muon (new CDF results soon) or delayed jet • Neutral • decay inside detector – delayed photons CDF analysis • decay outside detector – photon + MET planned analysis Exploring New Phenomena workshop

  14. Delayed Photon Analysis • Relies on EM calorimeter timing detector Measure photon arrival time background signal Exploring New Phenomena workshop

  15. Search for Delayed Photons Interpret in GMSB No new physics found here, so far signal region Exploring New Phenomena workshop

  16. Signature-based searches for dileptons + X at CDF • Look for excess above SM prediction in dilepton +X (X = photon, lepton, b-jet, HT, Missing ET; dileptons can be same-sign or opposite-sign) • Set cuts on first 1/3rd of dataset,apply to larger dataset • can be further applied to many models; e.g. heavy quarks as first example Dilepton (ee, mm, em) + high HT Good agreement in HT<200 control region. No excess, but one event at HT=900! HT == scalar sum of electron and jet ET, muon pT, missing ET Exploring New Phenomena workshop

  17. High mass dileptons • High ET electrons, optimized to look for high-mass resonances (150-950 GeV) • Applied to spin-1 Z’ and spin-2 RS Graviton 19% pe’s have 2E-3 Exploring New Phenomena workshop

  18. Set limits on SM-like Z’ Combine limits with diphoton on coupling vs graviton mass in RS model Exploring New Phenomena workshop

  19. Search for Massive Resonances Decaying to ZZ eeee Spectacular signature!! Model: RS Gravitons can decay to ZZ, sxBr=292fb (0.66 events expected in 2 fb-1 – not yet sensitive) Signal region M(eeee) 500-1000 GeV Exploring New Phenomena workshop

  20. Like-Sign dileptons • Signature-based search • Currently: chargino-neutralino production Basic selection: expect 34+/-4, see 44 Tight selection: expect 8 +/- 1, see 13 Exploring New Phenomena workshop

  21. MET + Jets • Signature: monojet events • Model: LED (ADD) • Graviton production leads to excess (not resonance) Set limits on MD vs N extra dimensions Exploring New Phenomena workshop

  22. MET + jets in SUSY Search for squarks/gluinos in MET + jets Add flavor tagging for stop/sbottom Exploring New Phenomena workshop

  23. Vista/Sleuth – the ultimate signature-based search • Algorithm to look at Tevatron data globally • Because new physics will probably not show up where we are expecting it • Look in hundreds of final states simultaneously • Vista – look at bulk distributions, find compatibility with SM (chi-square fit) • Sleuth – look in hi-pt tails • Flag a final state as “interesting” • Show us where to look in more detail • Further steps Quaero and Bard…to interpret new physics Exploring New Phenomena workshop

  24. summary • Tevatron searches are going at full steam • Lots of analyses ongoing, new and interesting results coming out • No new physics yet, but we remain hopeful • Need to focus our efforts for the full Tevatron dataset • What can we learn from what we’ve already done, to plan for the future? • We’ve tried to cover as much as possible, but are we overlooking important signatures, models? • Theoretical guidance for our program of Searches for New Physics Exploring New Phenomena workshop

  25. Backup Slides Exploring New Phenomena workshop

  26. SM and Other Backgrounds SM Collisions 4 sources, all estimated from data Collision photons from SM • Right vertex • Wrong vertex Non-collision “look-like photons” • Beam Halo • Cosmics Beam Halo Signal Monte Carlo Cosmics How do I know how each background looks like? Can not use photons. Signal (Blinded) Region Exploring New Phenomena workshop

  27. Highest Mass Diphoton Event (604 GeV/c2) Exploring New Phenomena workshop

  28. Highest Mass Diphoton Event Exploring New Phenomena workshop

  29. Top dilepton event at HT=900? Leptons: e 28 GeV, m 159 GeV Jets : 216 GeV (b-tag) 199 GeV 156 GeV 15 GeV MET: 90 GeV Exploring New Phenomena workshop