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Update on Z’ discovery potential in a bulk Randall- Sundrum model

Study on the discovery potential of Z' in a Bulk Randall-Sundrum model, considering electron and muon channels. Comparison of selection efficiencies between FullSim and AtlFast simulations. New definition of signal integrating windows for computation. Results show potential for discovery up to 8 TeV with 300 fb-1.

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Update on Z’ discovery potential in a bulk Randall- Sundrum model

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  1. Update on Z’ discovery potential in a bulk Randall-Sundrum model Julien MOREL Fabienne LEDROIT Gregory MOREAU ATLAS Exotics group IN2P3 – CNRS - LPSC - Grenoble 20 / 02 / 2007 – Exotics meeting

  2. Reminder … • We study the Z’ discovery potential for a Bulk Randall-Sundrum model • We look at 3 points in agreement with the EW constraint • Last meeting : • Results obtained for the electron channel • Using Z’ selection efficiency computed with AtlFast simulation v12.0.4

  3. Outline • Today : • FullSim / AtlFast comparison for the Z’ selection efficiency • FullSim of Z’->ee @ 7 TeV in 12.0.31 • New definition of the signal integrating windows for the discovery potential computation . • Study of the muon channel

  4. FullSim / AtlFast comparison for the Z’ selection efficiency – 1/2 AtlFast v12.0.4 FullSim v12.0.31 • Surprising low electron reconstruction efficiency with AtlFast • Due to : • the default isolated cut in AtlFast is : • for high Eele, can be above 10 GeV • FastAOD contains only isolated electrons.

  5. FullSim / AtlFast comparison for the Z’ selection efficiency - 2/2 If we remove the electron isolation cut in AtlFast : AtlFast v12.0.4 without isolation cut AtlFast v12.0.4 Electron reconstruction efficiency near 100% has expected with AtlFast We have to reprocess the electron channel study with an appropriate isolation cut

  6. New definition of the signal integrating windows - 1/2 To compute the discovery potential, we had taken into account the destructive interference between the Z’ and the DY process. In fact, even for 300 fb-1there is no DY event for mll > 3 TeV. (Cf. Dilepton invariant mass spectrum slide 2) We only search for an excess of event above a threshold.

  7. New definition of the signal integrating windows - 2/2 Z’ width and mass threshold Z’ Width @ MZ’=4 TeV Γ = 800 GeV for point A (0.2 MZ’) Γ = 200 GeV for point B (0.05 MZ’) Γ = 170 GeV for point C (0.04 MZ’) • For the widest point, 3Γ correspond to 0.6 MZ’ : • We look for signal above 0.6 MZ’ . •  Wekeep the same significance convention ( ). •  We add a criteria : we ask for at least 10 signal event.

  8. Study of the muon channel - 1/3 Z’ selection efficiency up to 10 TeV in the muon channel • Selection criteria forZ’-> mm • 2 μ± with |η|<2.5 • 2 identified μ ± • back to back in the transverse plane Fast simulation v12.0.4 ≈ 60% Muons selection efficiency rather flat and around ≈ 60% for mll>2TeV

  9. Z’RS discoverypotential for point B in the muon channel Point B 300 fb-1 Point B 100 fb-1 Less than 10 signal events • ATLAS can discover up to 5.3 TeV with 100 fb-1 • ATLAS can discover up to 5.7 TeV with 300 fb-1

  10. Z’RS discoverypotential for point A and C Point A 300 fb-1 Point A 100 fb-1 • up to 7 TeV with 100 fb-1 • up to 8 TeV with 300 fb-1 Point C Point C 300 fb-1 Point C 100 fb-1 • up to 3.6 TeV with 100 fb-1 • up to 4 TeV with 300 fb-1

  11. Outlook • Reprocess electron channel study with an appropriate electron isolation cut in AtlFast • Combine electron and muon (non universal couplings) • Write a note

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