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Analysis of Helicity and Cross Sections from 1999/00 e+p Data in the SFEW Review Meeting

In a comprehensive analysis presented during the SFEW Review Meeting on June 5, 2001, the results and methodologies regarding the measurements of xF3 and F2 using e+p data from the 1999/00 and 1996/97 runs were discussed. The analysis covers statistical errors, event selection, control plots, and comparisons with prior measurements. Detailed insights into the data processing techniques, including the use of Monte Carlo simulations, corrections, and systematic error assessments, were highlighted, along with preliminary results on single and double differential cross sections.

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Analysis of Helicity and Cross Sections from 1999/00 e+p Data in the SFEW Review Meeting

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  1. Neutral Current 1999/00 e+p • Since DIS01: • xF3 and helicity plot from Matthias • My analysis: • Data sample and event selection • Control plots • Results Chris Cormack Matthias Moritz Henning Schnurbusch Ricardo Gonçalo 5th June 2001 SFEW Review Meeting 5 June 2001

  2. Since DIS01: Matthias’ results: xF3 from 1998/99 and 1999/00 with systematics (same systematic error treatment in both data sets) SFEW Review Meeting 5 June 2001

  3. Matthias: Helicity plot in NC Draft NC 99/00 paper for Budapest: http://www-zeus.desy.de/~schnurbu/ZEUS/talks_ps/budapest.ps Please read and send comments SFEW Review Meeting 5 June 2001

  4. My Analysis • Summary: • Statistical errors only. • No background subtraction or RapGap Monte Carlo yet. • Used Orange release 2000a.2. • Measured F2 using 1999/00 e+p data: compared to 1996/97 measurement. • Measured xF3using 1998/00 data. • Reconstruction: • Electron finder: SINISTRA, FINDIS option 5. • Hadronic final state: CorAndCut. • Kinematic variables: Double Angle. • Electron track angle taken if within CTD acceptance. • Corrections: • Data: noise suppression and RCALCorr (in orange). • Data/MC: dead material and non-uniformity corrections. • MC: Vertex reweighting (1999/00) and electron energy smearing (width=0.2; cutoff=4.0). SFEW Review Meeting 5 June 2001

  5. NC 99/00 e+p data/MC • My analysis - DATA: • Run range 33125 up to 37165 only • Integrated Lumi 57.6 pb-1 • DST bit 12 • Runs excluded by EVTAKE • Monte Carlo: funnel num98t3.1 • 2 pb-1 with Q2 > 25 GeV2 • 4 pb-1 with Q2 > 40 GeV2 • 64 pb-1 with Q2 > 100 GeV2 • 95 pb-1 with Q2 > 400 GeV2 • 253 pb-1 with Q2 > 1250 GeV2 • 407 pb-1 with Q2 > 2500 GeV2 • 1.6 fb-1 with Q2 > 5000 GeV2 • 8.6 fb-1 with Q2 > 10 000 GeV2 • 77 fb-1 with Q2 > 20 000 GeV2 • 220 fb-1 with Q2 > 30 000 GeV2 • 1104 fb-1 with Q2 > 40 000 GeV2 • 5661 fb-1 with Q2 > 50 000 GeV2 • Djangoh; CTEQ5D; Ariadne • Henning & Matthias: • Data: 56.7 pb-1 for Q2<800 GeV2 63.0 pb-1 for Q2>800 GeV2 • Run range: 33125-37715 • Runs excluded by EVTAKE and PRESTAKE for Q2<800 GeV2 (uncalibrated presampler) • Monte Carlo: Photoproduction and RapGap Monte Carlo included • Slightly different binning • A lot of systematic errors done • Still to compare to my analysis in detail SFEW Review Meeting 5 June 2001

  6. Selection cuts • General: • Sinistra probability > 0.9 • Ee > 10 GeV2 • -50 cm < Zvtx < 50 cm • Electron DCA < 10 cm • Energy in cone not from electron < 5 GeV2 • pT/ET < 4 GeV • Simple elastic QED Compton rejection • Cuts for e < 17º • 44. < E-pZ < 65 GeV • pT,e > 30. GeV • Cuts for 17º < e < 163º • pTRK,e > 5. GeV • Cuts for e > 17º • 38. < E-pZ < 65 GeV • Kinematics: • Q2 > 185 GeV2 (lower bound of first bin) • yel < 0.95 • Henning & Matthias: • Require electron with track if within CTD acceptance • Extra cut on Rcal electron radius > 175 cm SFEW Review Meeting 5 June 2001

  7. Unfolding & etc: Reduced cross section: Cross-check of the reduced cross section: Measurement of xF3: And F2EM: SFEW Review Meeting 5 June 2001

  8. Control plots SFEW Review Meeting 5 June 2001

  9. Control plots Reasonable agreement between Monte Carlo and data but must add PhP and Rapgap soon SFEW Review Meeting 5 June 2001

  10. Results: single differential cross section Unfolding: SFEW Review Meeting 5 June 2001

  11. Purity and efficiency SFEW Review Meeting 5 June 2001

  12. Results: double differential reduced cross section SFEW Review Meeting 5 June 2001

  13. Results: double differential reduced cross sections as a function of Q2 Bins to be excluded SFEW Review Meeting 5 June 2001

  14. Results: double differential reduced cross section SFEW Review Meeting 5 June 2001

  15. Results: xF3 from 1998/99+1999/00 SFEW Review Meeting 5 June 2001

  16. Results: F2em from 99/00 data Unfolding: SFEW Review Meeting 5 June 2001

  17. Results: F2em from 99/00 data SFEW Review Meeting 5 June 2001

  18. Systematics studies for 98/99: much in common with 99/00 Systematic errorstatus alignment complete/to be checked? Energy scale almost done/smearing?  CAL non-uniformity done  backsplash/ZUFO vs. CCut done  chimney/Supercrack/RCAL radius done  e-finder efficiency done  track matching efficiency done  RapGap bug fixed done  PhP normalisation & check to do  pilot bunches done  vertex distribution done  Compton study done  comparison e-finder/reconstruction done  trigger efficiency almost done  higher order EW terms under investigation  hadronisation started  SFEW Review Meeting 5 June 2001

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