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Techincolor and Heavy Top/B search

Techincolor and Heavy Top/B search. Tulika Bose Meenakshi Narain (Brown University) Work done in the context of Les Houches 2007. (Bose, Narain). Exotic top partners. Some BSM theories predict the existence of: heavy top quark partner heavy bottom.

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Techincolor and Heavy Top/B search

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  1. Techincolorand Heavy Top/B search Tulika Bose Meenakshi Narain (Brown University) Work done in the context of Les Houches 2007

  2. (Bose, Narain) Exotic top partners Some BSM theories predict the existence of: heavy top quark partner heavy bottom • Model suggested by Contino and Servant : arXiv:0801.1679 (2008) • “Discovering the top partners at the LHC using same-sign dilepton final states” • Perform a sensitivity study using CMS fast simulation samples: Figures from slides of a presentation by R. Contino (TH-CERN)

  3. Exotic top partners Some BSM theories predict the existence of: heavy top quark partner heavy bottom • Look for same-sign di-lepton states • reduces the ttbar background • Look for a resonant tW invariant mass peak (T5/3) Figures from slides of a presentation by R. Contino (TH-CERN)

  4. Hunting for a heavy T • Signal & background samples generated using Madgraph • Pythia showering/hadronisation • Quark/Jet matching a la MLM Signal BKG Table from Contino and Servant : arXiv:0801.1679 (2008)

  5. Hunting for a heavy T • Samples processed via Fastsim • CMSSW_1_6_8 • Iterative 0.5 Cone Jets • Correct Jets (jet_corrections_16X) Bkg combined according to expected cross sections

  6. Hunting for a heavy T • .. • 2 same sign isolated leptons • (electrons or muons) with || < 2.4 • pT > 50 GeV for the leading lepton • pT > 25 GeV for the second leading lepton. • Missing transverse energy > 20 GeV.

  7. Hunting for a heavy T • .. 1) • At least 5 jets with pT > 30 GeV and || < 5.0. • pT > 80 GeV for the second leading jet. • pT > 100 GeV for the leading jet

  8. CMS Discovery Potential • Background is under control for such a signal • Triggers: Single lepton, di-lepton (including e+mu and same-sign triggers); Lepton + jets • Estimate the following for T5/3 + B: • 5 observation: ~ 240 pb-1 • with sys errors: 30% for signal and 50% for bkg • with no sys errors: ~ 230 pb-1 • # of Signal events 25.8; bkg events: 0.96

  9. Reconstructing the heavy T • Reconstructing the first W (from top decay) (eff: 0.84) • Take the two jets with invariant mass consistent within 20 GeV of W boson. • If a btagged jet is found close to the second leading lepton, the jet is removed from consideration. • Require  Rjet< 1.5 and the W(pT) > 50 GeV. • Reconstructing the second W (from heavy exotic top) • Remove jets associated with first W. • Take the two jets with invariant mass consistent within 25 GeV of W boson. • Require  Rjet< 1.5 and the W(pT) > 30 GeV. W from top decay W from heavy top

  10. Reconstructing the heavy T • Reconstructing the heavy Top (from top decay) • Discard the four jets that were assigned to the two W bosons • Combine the btagged jet with one of the two W bosons to get the top quark • Take the one that is closest to top quark mass (within 40 GeV) • The top quark candidate is combined with the other W boson to yield the heavy top partner - T(-5/3) Recons. heavy Top and B top quark from heavy T

  11. Reconstructing the heavy T • efficiencies for reconstructing 2 W candidates and one top candidate. • With Mass reconstruction: • Estimate the following for T5/3 + B: 10 fb-1 • 3 evidence: ~ 250 pb-1 • 5 observation: ~ 650 pb-1

  12. (Bose) Technicolor aT; Extend TCSM2 to include aT

  13. Technicolor (Multiple lepton signature) High mass di-boson resonance: Technicolor signal: TC W Z(clean with leptonic W & Z decays) GeV fb fb fb

  14. Selection criteria

  15. Technicolor (Multiple lepton signature) Triggers: Single, di-leptons Selection criteria: • 3 isolated leptons (electron or muon) • Electron pT > 15 GeV, || < 2.5 • Muon pT > 15 GeV, || < 2.5 • Missing transverse energy • ET > 40 GeV • Two oppositely charged leptons with Z invariant mass • Leptonic HT (scalar sum of transverse momenta of leptons) > 150 GeV • Z pT > 65 GeV; • W pT > 65 GeV (computed using lepton and missing Et) Event Selection Efficiencies:

  16. CMS Discovery Potential 5 observation 10 fb-1 Promising LHC discovery channel with clean signature!

  17. T, aT Mass Reconstruction The two mass peaks for T and aT are not separated due to the Missing ET resolution. (ATLAS study sees a separation). After Reconstruction Generator Level aT RhoT

  18. Conclusion • CMS discovery potential for T(-5/3) and Technicolor decays to multileptons have been evaluated. • Work done via fastsim • Move to using full simulation and standard object IDs and corrections.

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