Same sign dilepton events with jets and large missing transverse energy at the LHC with CMS

1. Same sign dilepton events with jets and large missing transverse energyat the LHC with CMS Marc Weinberg University of Wisconsin Preliminary Examination Marc Weinberg, University of Wisconsin

2. Outline of talk • Introduction • The LHC and CMS • Kinematics and reconstruction • Searching for supersymmetry (SUSY) • Supersymmetry signals in CMS • Summary and plans Marc Weinberg, University of Wisconsin

3. CMS magnet • Want very high magnetic field in tracker: put solenoid inside muon chambers • Axial magnetic field of 4T; ~ 100,000 times magnetic field of Earth • Superconducting wire carries 20,000 A current • Solenoid will be cooled to ~ 4 K for operation Marc Weinberg, University of Wisconsin

4. Muon identification in L1 trigger • Link local track segments into distinct 3D tracks • Reconstruction in η suppresses accelerator muons • Measure pT, η and φ of muon candidates from reconstructed tracks Marc Weinberg, University of Wisconsin

5. Jet identification in L1 trigger • Jet ET • 12 x 12 trigger tower ET sums in 4 x 4 region steps with central region > others • Larger trigger towers in HF but ~ same jet region size, 1.5 η x 1.0 φ • Output • Top 4 jets in central rapidity and top 4 jets in forward rapidity max 4 x 4 region Marc Weinberg, University of Wisconsin

6. SUSY study work flow Decay simulation (SDECAY 1.2) SUSY spectrum (ISASUGRA 7.75) Hadronization (PYTHIA 6.409) Detector simulation (CMSSW GEANT) Reconstruction (CMSSW RECO) Analysis (CMSSW ANALYSIS) = steps performed for this analysis = next steps Marc Weinberg, University of Wisconsin

7. Selecting same sign dileptons • mSUGRA assumptions: • Same mass for selectron, smuon • Same couplings to other particles • Four different cases to consider: • Ordered by pT: • Previous studies only looked at • CMS Internal Note 2006/087 • Methodology: • Leptons ordered by decreasing pT • If exists, choose same-sign pair with largest pT • If two same-sign pairs found with opposite signs, choose lepton pair with largest scalar sum of pT Marc Weinberg, University of Wisconsin

8. Generator lepton pT requirement Require both generator ss leptons pT > 10 GeV Marc Weinberg, University of Wisconsin

9. Generator lepton isolation requirement Require leading ss lepton Iso < 10 GeV Require next-to-leading ss lepton Iso < 6 GeV Marc Weinberg, University of Wisconsin

10. Generator jet multiplicity requirement All jets shown: ET > 50 GeV Require ≥ 3 jets Marc Weinberg, University of Wisconsin

11. Generator jet ET requirement Require next-to-next-to-leading jet ET > 55 GeV Require next-to-leading jet ET > 130 GeV Require leading jet ET > 175 GeV Marc Weinberg, University of Wisconsin

12. Generator missing ET requirement Require missing ET > 200 GeV Marc Weinberg, University of Wisconsin

13. Signal identification Marc Weinberg, University of Wisconsin

14. Results from MC study of same sign dimuons • Study: CMS Internal Note 2006/087 • Plot: missing ET • SM events (shaded area) and LM1 (solid line) • Normalized to integrated luminosity 10 fb-1 • Table: number of events passing requirements • SM backgrounds and LM1 • Note: missing ET powerful discriminator Marc Weinberg, University of Wisconsin