1 / 18

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.

kalb
Download Presentation

Techincolor and Heavy Top/B search

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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.

More Related