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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.

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W’ and Z’ with 10 fb -1 of data

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  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

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