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WGRAD 2 nd photon study

Yu Zeng Duke University. WGRAD 2 nd photon study. Wgrad 2 nd photon study (Z->ee) ‏. Generate Z->ee events using Pythia - three Z mass values (90687, 91187, 91687) - 100m events at each mass (3 x 100m) - used for Z mass scan

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WGRAD 2 nd photon study

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  1. Yu Zeng Duke University WGRAD 2nd photon study W Mass Workshop

  2. W Mass Workshop Wgrad 2nd photon study (Z->ee)‏ • Generate Z->ee events using Pythia - three Z mass values (90687, 91187, 91687) - 100m events at each mass (3 x 100m) - used for Z mass scan • Call Wgrad the 2nd time - when the 1st photon energy is greater than 4 MeV. • Compare Z mass value between 1-photon and 2-photon cases: - 16 MeV shift

  3. Pseudo-experiment vs. template (Z->ee)‏ 1- vs. 1- 2- vs. 2- 1- vs. 2- 2- vs. 1- Pseudo-exp. vs. template

  4. W Mass Workshop Observed problems (Z->ee)‏ • If always call Wgrad the 2nd time, Z mass value shift between 1-photon and 2-photon (always) is: - still 16 MeV • 2-photon (4 MeV) vs 2-photon (always): - no shift • 1g vs. 1g : 91192+/-1 chi2/df=48/38 • 1g vs. 2g-always: 91206+/-1 chi2/df=65/38 • 2g-always vs. 2g-always: 91197+/-1 chi2/df=42/38 • 2g-always vs. 1g : 91182+/-1 chi2/df=70/38 • 2g-4MeV vs. 2g-always: 91193+/-1 chi2/df=80/38 • 2g-always vs. 2g-4MeV: 91197+/-1 chi2/df=30/38 Pseudo-exp. vs. template

  5. W Mass Workshop 2nd photon study (Z->mm)‏ • Use the same Z->ee events generated from Pythia - three Z mass values (90687, 91187, 91687) - 100m events at each mass (3 x 100m) - used for Z mass scan • Call Wgrad once vs. call Wgrad twice always- no matter what the 1st photon energy is. • Compare Z mass value between 1-photon and 2-photon cases- no shift

  6. Pseudo-experiment vs. template (Z->mm)‏ 1- vs. 1- 2- vs. 2- 1- vs. 2- 2- vs. 1- Pseudo-exp. vs. template

  7. W Mass Workshop Summary • 16 MeV shift in Z->ee channel between 1photon and 2photon - but no difference between two cases: 1) 2nd photon is always generated and 2) 2nd photon is generated only when 1st photon energy > 4 MeV • No shift in Z->mm channel between 1photon and 2photon

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