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The IReS Strasbourg group in D Ø

The IReS Strasbourg group in D Ø.

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The IReS Strasbourg group in D Ø

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  1. The IReS Strasbourg group in DØ • STAFF: 12 people 1 under-graduate (6 months): Vincent SICCARDI 4 PhD's: Sébastien GREDER (2004, ULP, ttbar cross-section), . Anne-Catherine LE BIHAN (2005, ULP, neutralino search), . Jean-Laurent AGRAM (2005, UHA, jet cross-cection), . Benoit CLÉMENT (2006, ULP, single top evidence) 1 postdoc (6 months): Arnaud GAY (UHA, tau identification) 6 senors: .Daniel BLOCH, Walter GEIST, Denis GELÉ, Isabelle RIPP-BAUDOT (CNRS), . Abdenour LOUNIS (ULP univ.), François CHARLES (UHA Univ.) • 4 PHYSICS SUBJECTS: .- ttbar cross-section with b-tagging:.Sebastien GREDER, Vincent SICCARDI, D.BLOCH, I.RIPP-BAUDOT.- single top with b-tagging:Benoit CLEMENT, D.GELE, D.BLOCH.- neutralino search with tau identification:.Anne-Catherine LE BIHAN, Arnaud GAY, A.LOUNIS, F.CHARLES. - jet inclusive cross-section:Jean-Laurent AGRAM, F.CHARLES Abdenour Lounis (IReS/ULP Strasbourg)

  2. b-quark tagging (D.Bloch, B.Clément, S.Greder, D.Gelé, I.Ripp-Baudot) based on Impact Parameter significance of all tracks in jets: use negative IP for calibration, tag with positive IP tracks résolution b-enriched IP /  Combine all IP informations into a Jet LIfetime Probability, use real data to estimate b-tag (from muon-in-jets) and mistag (from multi-jets) efficiencies already used in various channels: top, Higgs, … Abdenour Lounis (IReS/ULP Strasbourg)

  3. ttbar cross-section strong coupling • Apply loose selection cuts on lepton+jets, but use JLIP b-tagging to enrich in t→Wb events • Evaluate all background sources from real data (QCD) and MC (W+jets) • Apply b-tag and mistag efficiencies from real data • Compute the excess in W+3 jets or W+4 jets: ttbar ! t→Wb, W→lepton tbar→Wb, W→2jets e + jets μ + jets ttbar ttbar jet multiplicity Abdenour Lounis (IReS/ULP Strasbourg)

  4. ttbar candidate with 2 b-tagged jets ! Abdenour Lounis (IReS/ULP Strasbourg)

  5. single top search • Similar to the ttbar measurement, but more inclusive approach • This process has never been observed: expected in W+2 jets • Only a limit on the production is given yet • Would allow to measure |Vtb| with a larger statistics single top electroweak coupling Vtb ttbar Abdenour Lounis (IReS/ULP Strasbourg)

  6. Looking for neutralino SUSY particules with tau and leptons final states (A.-C. Le Bihan, A. Gay, A. Lounis, F. Charles) tau lepton identification by using 3 Neural-Networks: : combined use of calorimeter cells deposits and tracking Decay of with coupling if R-Parity Violation : ⁺ ⁺ ⁺ ⁻ ⁺ ⁻ ⁻ shower profile variable before/after applying NN Z→ background Abdenour Lounis (IReS/ULP Strasbourg)

  7. QCD test with high Et jets (J-L. Agram, F. Charles) • Test QCD by the jet inclusive cross-section at high Et and at high rapidity • Compare with structure function models (gluons at high x) • An excess maybe the sign for new physics • Need very goood handling of jet energy scale corrections Abdenour Lounis (IReS/ULP Strasbourg)

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