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Controlling the Neutral Drell-Yan at high mass

Controlling the Neutral Drell-Yan at high mass. Samir Ferrag University of Glasgow. ATLAS UK Physics Meeting, Durham, 09-11/01/2008. Introduction. Context : high mass Dilepton-Analysis with ATLAS: Standard Model + Detector ---> New Physics (afternoon talk) Question:

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Controlling the Neutral Drell-Yan at high mass

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  1. Controlling the Neutral Drell-Yan at high mass Samir Ferrag University of Glasgow ATLAS UK Physics Meeting, Durham, 09-11/01/2008

  2. Introduction • Context: high mass Dilepton-Analysis with ATLAS: Standard Model + Detector ---> New Physics (afternoon talk) • Question: • How much do we control the Standard Model ? • Mini-Workshop in Glasgow: • kindly funded by SUPA* and Glasgow Physics Department http://ppewww.physics.gla.ac.uk/~samir/MiniWorkshop/ • Working group: • F. Piccinini, S. Moretti, C. Carloni, C. Sephered, J. Jackson, S. harper, A. Viccini, S. Pozzorini, B. Jantzen, D. Wackeroth and S. Ferrag • Goal: • bring together knowledge of QCD and ElectroWeak theories and apply it to a Dileptons at high mass for the best possible theoretical prediction might be tested with early LHC data * SUPA for Scottish Universities for Physics Alliance

  3. Output (Preliminary) 0- Introduction 1- QCD 1.1- Existing tools and calculations 1.2- Effects of NLO corrections 2-EW 2.1- NLO corrections 2.2- Multiples photons emissions 2.3- Sudakov Logs 1-loop vs Sudakov approx, 2-loops Sudakov 3- Combined effects Combination @ parton level + combination @ shower level 4- Uncertainties 4.1 PDFs 4.2 Energy scale (QCD, QED) 4.3 Input Scheme 4.4 Others a-QED+QCD b-NNNLO… c-Shower… 5-Summary and Conclusion 5.1- Summary and results 5.2- Conclusion

  4. Calculating the Drell-Yan Cross section Change the W by Z

  5. Status of QCD calculation and tools - - - - - -

  6. QCD NLO corrections I

  7. QCD NLO corrections II

  8. EW calculations and tools for Z - -

  9. 2-Loop EW Sudakov logs • From Virtual Weak boson corrections: • large log EW corrections: • - 1-Loop >> 10% • - 2-Loop >>1% • Asymptotic expansion at high energy for M2W/s << 1 • Typical size of the leading 2-loop logarithms: • Strong simplification, process independent treatments • Good precision • Using the 2-loop EW Sudakov logs is a good approximation to • full EW 2-loop calculation

  10. Testing the 1-loop EW Sudakov Preliminary Comparison 1 Full Loop calculation ZGRAD2 and LO+1-loop Sudakov

  11. EW: 2-loop Sudakov Logs Preliminary 2 loop Sudakov calculated and injected into HORACE

  12. Combining QCD and EW corrections At LO, the MC are tuned to agree @ 0.1% level

  13. Corrections on invariant mass Preliminary No QCD LL

  14. Pt of the lepton pair Preliminary No QCD LL

  15. Pt of the lepton Preliminary No QCD LL

  16. Lepton and lepton pair rapidities Preliminary No QCD LL No QCD LL

  17. Conclusion • Successful interaction experimentalists-theorists • Toward a control of the high mass dileptons and precision predictions • Further work: uncertainties • Results will be injected and used in the ATLAS CSC • …

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