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Exploring New Phenomena at CDF

Exploring New Phenomena at CDF. Jane Nachtman (Fermilab) for the CDF collaboration. Objective. This workshop is about bringing theorists and experimentalists together to focus on maximizing the Tevatron’s discovery potential

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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

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