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Small Extra Dimension Graviton Detection at ATLAS

Small Extra Dimension Graviton Detection at ATLAS. Looking at the Graviton as it decays through G*->Z 0 Z 0 ->e - e + e - e + Audrey Todhunter Case Western Reserve University Dominik Dannheim Columbia University. The Graviton.

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Small Extra Dimension Graviton Detection at ATLAS

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  1. Small Extra Dimension Graviton Detection at ATLAS Looking at the Graviton as it decays through G*->Z0 Z0 ->e-e+e-e+ Audrey Todhunter Case Western Reserve University Dominik Dannheim Columbia University

  2. The Graviton Massive graviton resonances are predicted by models using extra dimensions -resonances could be well separated in mass The graviton couples universally (ee,,,,Z0Z0, etc…) -Products could be detected at ATLAS Analysis used the Randall-Sundrum model, which predicts the mass of the first resonance by: mn =xn(k/MPl) We chose k/MPl=0.01 to give resonances on the TeV scale

  3. This analysis: ppG*Z0Z0e+e-e+e- against a Standard Model background qqZ0Z0e+e-e+e- The branching ratio Br for Z0Z0e+e-e+e- is only 3.4%*3.4% = 11.56% for this decay process

  4. Signal and Background Simulation -Pythia event generator -mass points at 300GeV, 500GeV, 700GeV, 1TeV, and 1.5TeV, as well background processes around each point -want to know how well these signals can be detected at ATLAS Geant4 used in a full simulation of the ATLAS reconstruction

  5. Properties of simulated signal and background

  6. Particle Selection We can identify electrons by their characteristics detected in the EM calorimeter and the central tracker • Transverse energy eT > 20 GeV • Likelihood > 0.9 being electron rather than pion • 2e+e- pairs in each entry - best combination of particles decided by comparing reconstructed Z0 mass to known Z0 mass (91.1GeV)

  7. Invariant Z0 mass from a 300GeV signal: from electron pairs closest to Z0 mass within each interaction

  8. Graviton Reconstruction -electrons chosen for Z0 mass used to reconstruct invariant G* mass -signal scaled for 100 fb-1 luminosity (1 year running at design luminosity) NEv = (·Br) · L imposing a weight factor on the number of simulated events

  9. Signal at 500GeV with a Gaussian fitsigma parameter used to look at events within a mass window of ±3

  10. Signal and background added and fit with[p0]e(-(x-[p1])2/2[p2] 2+ [p3]e([p4]x+[p5])

  11. Potential discovery of resonances fromG*Z0Z0e+e-e+e-at ATLAS • count number of signal and background events within the ±3 window • need to have Nsig>5√ (NBG) or Nsig >10 for a statistically significant signal • number of events can be increased by raising luminosity

  12. Luminosity needed for Nsig>5√ (NBG) or Nsig >10 L=100fb-1: one year running at design luminosity

  13. Conclusions -for the processG*Z0Z0e+e-e+e-the upper mass limit is slightly below 700GeV -higher discovery potential at increased luminosity -other decay channels are possible for the graviton which may have higher upper limits for detection

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