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Some clarification on how the main background is rejected

This presentation delves into clarifying methods to reject the main background in high-energy physics experiments and improve detector performances. Simulations and analysis of mass values and detector effects are discussed for various processes. Strategies such as utilizing electron high energy tagging, rejecting electrons above certain energy thresholds, and employing b-tagging with VDET for WW/ZZ separation are explored. Key emphasis is placed on the significance of PFLOW performance in achieving accurate analysis results.

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Some clarification on how the main background is rejected

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  1. WW / ZZ separation Some clarification on how the main background is rejected how the detector performances are involved J.C. BRIENT

  2. ∆EJ = 0.60 EJ ∆EJ = 0.30 EJ Simulation with Simulation with Mass J3 J4 (GeV) Starting point Mass J1 J2 (GeV) This presentation Add background e± W∓ Effect when using the VDET btag Quantify the results with S/N ratio for different searches J.C. BRIENT

  3.  Select 4 jets Mass J3J4 (GeV) Simulation with ∆EJ = 0.30 EJ Mass J1J2 (GeV) Cross sections (fb) ZZ,WW,eWZ, J.C. BRIENT

  4. Processes 1 2 3 ZZ, WW, eWZ, With all decays to jets. In the fiducial volume of the detector, an isolated electron with high energy is a good tagging for process (3) ALL processes Process (3) Electron energy (GeV) J.C. BRIENT

  5. Reject if Electron Energy >100GeV (50 at low angle) MM2<500 and Electron Energy >5GeV MM2<250 and Electron Energy >2.5GeV The low angle coverage for electron is ESSENTIAL process e+ e− → e± W∓ Z (blue) almost disappears, while leaving processes (1) and (2) unchanged Mass J3 J4 (GeV) Mass J1 J2 (GeV) J.C. BRIENT

  6. ≈ 12.2 S(ZZ) B(WZ,WW) Select ≥ 2 b-jets Mass J3 J4 (GeV) Mass J1 J2 (GeV) J.C. BRIENT

  7. ≈ 100 ≈ 18.6 ≈ 2.4 S(WW,ZZ) B(WZ) S(WW) B(ZZ, WZ) S(ZZ) B(WW, WZ) WW region: Contains 89 % of the WW and ZZ region: Contains 71 % of the ZZ Select < 2 b-jets Before di-jet mass cut After cut J.C. BRIENT

  8. Other relevant backgrounds seem easier to remove (guess) i.e. WW, Z() could be rejected with missing energy and mass • e±W∓ background can be removed easily (with a good electron id. at low angle ) • the main problem is still the WW/ZZ separation • For ZZ rejection, a good VDET btag can help • the PFLOW performance is still the key point for the analysis J.C. BRIENT

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