1 / 25

W’ and Z’ with 10 fb -1 of data

W’ and Z’ with 10 fb -1 of data. Kamal Benslama Kevin Black Stephane Willocq. Outline. Introduction: Why Z’/W’ What we know today Basic Theoretical Framework Current Bounds What we can hope to do in 10 fb -1 of data? Update of Z’ Rome Analysis Start of W’ Analysis Plans.

chas
Télécharger la présentation

W’ and Z’ with 10 fb -1 of data

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. W’ and Z’ with 10 fb-1 of data Kamal Benslama Kevin Black Stephane Willocq

  2. Outline • Introduction: Why Z’/W’ • What we know today • Basic Theoretical Framework • Current Bounds • What we can hope to do in 10 fb-1 of data? • Update of Z’ Rome Analysis • Start of W’ Analysis • Plans

  3. Introduction: Why new Gauge Bosons? • Standard model based on local gauge invariance • SU(3)C x SU(2)Wx U(1)Y • Natural to ask: Are these all of the fundamental interactions of nature? What are the limits on more? • The Standard Model is an effective theory – likely to break down at the electroweak scale – natural to think that we might find evidence for new gauge forces at this scale

  4. What kind? • Three types • Confined: Perhaps some of the particles we see today are composites bound by some new confined force (eg, Top color) • Coulomb: More forces that are so week we haven’t seen them yet • Higgs type: Heavier cousins of the W and Z getting mass from some scaled up version of the Higgs • Focus on new Gauge Bosons with Standard Model like coupling • First worry about finding ‘new’ physics, then find out what it is

  5. Where could the Z’/W’ come from? • Many good reasons to look for new gauge bosons (just as we look for new fermions) • Many theories argue for the existence of new gauge bosons to shed light on mysteries of the SM • GUT with large gauge groups break down to SM + extra gauge bosons at lower energies • Extra Dimensions- Bulk has copies (KK modes) of SM gauge bosons which are massive • TopColor->break electroweak symmetry breaking • Little Higgs • New SUSY theories

  6. Limits MW’ > 842 GeV (205 pb-1) MZ’ > 845 GeV(448 pb-1) *Br < 24 fb

  7. Samples • Samples: Z’  +- with SM-like couplingsSamples generated and simulated at U. MontrealPythia process 141: q q-bar  gamma*/Z/Z’  +-with low mass cutoff of 500 GeV for SSM 1000 & SSM 2000 1000 GeV for SSM 3000 & SSM 4000 • • • Note: BF(g/Z/Z’  +-) factored into the calculation of the luminosity 1 TeV W’->l nu with SM-like couplings (Benslama/Black) 10.0.1 20 K events, W-> (*BF= 3312.6 fb) 4.8 fb-1

  8. Muon Perfomrance at very high Pt Muon (AOD) efficiencies & resolution (rel.10.0.4) efficiency efficiency

  9. Z’->  • Event Requirements • Two Muons with opposite charge • ||<2.5 • pT> 10 GeV • less than 20 GeV of energy in cone of 0.4 around muon • HighPt Algorithm only, both inner detector and muon spectrometer track

  10. Invariant Mass Distributions (1 TeV) Fit to Breit-Wigner + 1st order polynomial Fit to Gaussian + 1st order polynomial

  11. At 2 TeV Fit to Breit-Wigner + 1st order polynomial Fit to Gaussian + 1st order polynomial

  12. At 3 TeV Fit to Gaussian + 1st order polynomial

  13. At 4 TeV Not enough statistics for fit  ignore

  14. Z’ Summary Simple fit to a Gaussian + 1st order polynomial anticipated number of observed Z’  +- signal decays

  15. Z’ Backgrounds

  16. Background Distribution Apply all cuts except: dimuon charge, high-pT alg and combined mu requirements Plots normalized to 10 fb-1

  17. Background Distributions Apply all cuts except: dimuon charge, high-pT alg and combined mu requirements Plots normalized to 10 fb-1

  18. Background Distributions • Apply all cuts

  19. Background Distributions • Apply all cuts

  20. W’ Signal and Background • Selection • ET > 100 GeV • Muon • Isolated, • highPt Algorithm only • both inner and muon detector track (pT match within 20%) • pT > 75 GeV

  21. Backgrounds

  22. W’ Signal and Background

  23. W’ Summary

  24. Event Count • For simple cuts, 3987 events for a 1 TeV W’ in 10 fb-1 of data • Most backgrounds are very small after cuts, however in the far tails of the distribution need more MC to extract meaningful numbers (study W->l nu in fast MC to get a better estimate) , fakes will take more work to get a reasonable handle on

  25. Conclusions and Plans • As expected, backgrounds for both Z’ and W’ appear very small (though long tail of Drell-Yan needs to be very well understood) • Both should be “easily” observable up to a few TeV with 10 fb-1 of data • Plans • Continue to work on reconstruction performance (wanted to use more recent version of simulation/digitization/reconstruction – but some bugs) • November, trigger simulator should be in testing stage (Black) has agreed to test muon trigger for UTF. Use Z’, W’ as test case. • Look at e, and  channels

More Related