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SUSY Searches at the Tevatron

SUSY Searches at the Tevatron. Alexei Safonov University of California, Davis For CDF and D0 Collaborations. Tevatron Status. Upgrades for Run II: Main Injector (150 GeV proton storage ring replaces Main Ring. Shorter interbunch spacing (396 ns) Beam Energy: CM 1.96 TeV

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SUSY Searches at the Tevatron

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  1. SUSY Searches at the Tevatron Alexei Safonov University of California, Davis For CDF and D0 Collaborations

  2. Tevatron Status • Upgrades for Run II: • Main Injector (150 GeV proton storage ring replaces Main Ring. • Shorter interbunch spacing (396 ns) • Beam Energy: CM 1.96 TeV • Instantaneous Luminosity: • 4.1 x 1031 cm-2s-1 peak luminosity • Expected Goals: • 250 pb-1 by Summer 2003 • 2000 pb-1 for Run IIa

  3. Status of the Detectors CDF Integrated Luminosity

  4. Many Faces of SUSY • SUSY has many faces: • MSSM (LSP is , Signature isgenerally leptons, jets and MET) • mSUGRA (LSP is or , Signature isgenerally leptons, jets and MET) • 3rd Generation/High tanb(mixing  light stop/stau, many taus in final state) • RPV (LSP varies, Signature is more leptons, lessMET. We concentrate on RPV couplings that lead to lepton number violation) • GMSB (LSP is gravitino, leptons or photons and MET) • AMSB ( , – near mass-degenerate, more difficult experimentally and requires special treatment)

  5. Run II and SUSY Searches • In many cases, setting competitive limits requires • large luminosity • going to the low end in energies (cascade decays and massive escaping ) • sharp cuts between signal and background • Thorough understanding of backgrounds and calibrated detector response at low transverse momentum • Presented Run II results mostly refer to scenarios at higher end of energy spectra. • Updated Run I results utilize improved knowledge of those “difficult” lower energies.

  6. At Higher End of Energies: Z’ • Typical high energy end study: • ET>20 GeV • PT>13 GeV • Calorimeter Iso/ET<0.1(0.2) • … • Limits on Z’ and Graviton extracted. • Can be used to set SUSY limits.

  7. Low tanb SUSY: trileptons • mSUGRA: • Cuts: • 2e: PT>15(10), • 10<Mee<70 • MT(e,MET)>15 • Iso Track PT>5,|h|<3 • MET>15 • No events observed (0.0+/-1.4 expected) • D0, Run II, 42 pb-1

  8. Search for MSSM Stop • Heavy top, mixing -> stop can be light • Updated CDF Search, Run I: 106 pb-1 • Lepton PT>10 GeV • Second Lepton PT>10 GeV • MET>30 GeV • BG: DY, bb,cc, fakes.

  9. SUSY at higher tanb • Consider standard trilepton search: • Large tanb is theoretically motivated • At tanb >8 final state leptons are dominated by t’s. • Tau channels are very important in Run II!

  10. Run II: Advances on Tau Front • Taus were traditionally more “difficult” for both experiments. Clear need for a significant improvement. • CDF Lepton+Track (LT) Triggers: • Lepton PT>8 GeV (electron or CMUP/CMX muon) • Tau-style isolated 5 GeV track • Targets multilepton final states including taus. • Installed and commissioned in January 2002.

  11. CDF: W/Z->tau tau • Hadronic Tau track multiplicity: • Fit of the data to the MC signal predictions plus expected shape of the jet fake backgrounds • Mass plot (OS data only): • Signal normalization as in the mutiplicity plot, fit for the fake fraction.

  12. D0: Z->tau tau • Tau Definition: • Calorimeter Cluster R=0.4 • RMS(cluster size)<0.25 • At least 1 track

  13. Search for R-parity violation • Test 3rd gen. RPV coupling: • CDF, Run I: 106 pb-1 • Final state “looks like” LQ3 analysis. • Lepton(e,m)+t+Njets • Improvements: • Lower electron cut, PT>10 GeV • Track-based th id, include p0 reconstruction Significantly improves acceptance for Compared to earlier Run I studies

  14. Search for R-parity violation • CDF Run I: L=106 pb-1 2TeV

  15. NLSP Signature (assuming has long lifetime) – two non-pointing photons+MET Searches for GMSB • D0 (Run II, 42 pb-1): • 2EM Clusters Et>20 GeV, |h|<1.1 • EM clusters point to same vertex • Jets cone 0.7 • Dq (leading jet, MET) < 2.6 • No jets in 1<|hdet|<1.5

  16. Searches for GMSB • D0 Limit set for: • Messenger mass scaleMm=2 L • Equiv. # of 5+5 m-fieldsN5=1 • tanb=15 • sign(m)>0 Run II Limit: Run I:

  17. Conclusions • Tevatron operating at world’s highest energy • Both experiments are commissioned and taking physics data. • First Run II results available in an assortment of SUSY models tested (mostly in the high ET region). • Higher CMS energy allows competitive results with Run I even at lower luminosities. • Competitive SUSY results will need more time, both in terms of luminosity and in detailed understanding of the detector efficiencies and backgrounds in the low ET region. • CDF and D0 carefully including tau leptons to searches for new physics now • More analyses to come soon.

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