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ZEUS EW fits-report request for preliminary 6 th Aug 2007

ZEUS EW fits-report request for preliminary 6 th Aug 2007. A.M.Cooper-Sarkar and C. Gwenlan – team-1 S. Shimizu and K.Nagano– team -2. Report on fitting new data on e- NC polarised Electroweak NC couplings: au ad vu vd. Introduction. Status @ DIS06 preliminary

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ZEUS EW fits-report request for preliminary 6 th Aug 2007

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  1. ZEUS EW fits-report request for preliminary6th Aug 2007 A.M.Cooper-Sarkar and C. Gwenlan – team-1 S. Shimizu and K.Nagano– team -2 • Report on fitting new data on e- NC polarised • Electroweak NC couplings: au ad vu vd

  2. Introduction Status @ DIS06 preliminary • HERA II data: 04/05 CC and 04/05 NC (DIS06 prel.) – polarized e- • First fit including HERA-II data: ZEUS-Pol fit • Fits with free EW parameters • Mw, GF • au, ad, vu, vd: 2-param. free fits Fits with SM formalism (T, sin2thw) Updates for today • Fits were performed on • ZEUS-JETS data • 04/05 CC (DIS06 prel.) • 04/06 NC (DIS07 prel.) • 1. Update of ZEUS-Pol fit. 2. au, ad, vu, vd: 4-EW param. free in addition to PDF parameters

  3. Updated fit: Newly included NC cross sections Request preliminary New NC e- data with +ve polarisation P= +0.30 Lumi=71.8 pb-1± 3.5% New NC e- data with –ve polarisation P= -0.27 Lumi=105 pb-1± 3.5%

  4. Updated Fits: PDFs Request preliminary PDFs from the new fit compared to published ZEUS-JETS fit – central values of the PDFs hardly change at all…..

  5. Updated Fit: Fractional uncertainties Request preliminary BUT the PDF uncertainties are reduced at high-x, particularly for xuv…..as expected since NC and CC e- cross-sections are both u dominated

  6. PDF fits with NC 04/06 data are not a lot different than what you saw in 2006 with NC 04/05 data

  7. Fractional Uncertainties at high-Q2 Request preliminary e Improvement in uncertainty remains up to high scales- important for LHC physics!

  8. Team 2 analysis check (ZMVFN)

  9. Summary so far Nice improvement to PDF accuracy for high-x u valence Not dramatically different from 2006 But now we move on to fits with EW parameters free as well as PDF parameters In 2006 we could only free 2 NC coupling parameters at once because we fell into a double minimum with 4-EW parameters free--- The extra 05/06 NC data has resolved this problem. We would like to have preliminary status on these new EW fit results with 4-NC couplings free We don’t want to issue new results with only 2-NC couplings free..but these are in extras, if you are curious

  10. F20= Σi Ai0(Q2) [xqi(x,Q2) + xqi(x,Q2)] xF30= ΣiBi0(Q2) [xqi(x,Q2) - xqi(x,Q2)] Ai0(Q2) = ei2 – 2 eivivePZ + (ve2+ae2)(vi2+ai2) PZ2 Bi0(Q2) = – 2 eiaiae PZ + 4ai aevi ve PZ2 F2P = ΣiAiP(Q2) [xqi(x,Q2) + xqi(x,Q2)] xF3P= Σi BiP(Q2) [xqi(x,Q2) - xqi(x,Q2)] AiP(Q2) = 2 eivi ae PZ - 2 ve ae (vi2+ai2) PZ2 BiP(Q2) = 2 eiaive PZ - 2 ai vi (ve2+ae2) PZ2 Quark couplings to Z Now consider fits to electroweak NC couplings as well as PDF parameters The total cross-section : σ = σ0 + P σP The unpolarised cross-section is given by σ0 = Y+F20 + Y-xF30 The polarised cross-section is given by σP = Y+F2P + Y-xF3P PZ >> PZ2 (γZ interference is dominant) ve is very small (~0.04). unpolarized xF3 ai, polarized F2  vi

  11. Fits with ai, vi free as well as PDF parameters SM formalism ai = T3i , vi = T3i – 2ei sin2ƏW Request preliminary

  12. au/vu ad/vd au/ad vu/vd contours (RTVFN, ZJ) Request preliminary

  13. Comparison to the previous fit DIS06 Used to have a double minimum when 4-EW parameters free. The new NC data from 05/06 has resolved this

  14. central value total uncert. Team-2 contours (RTVFN, ZJ)

  15. Comparison with other experiments Request preliminary vd moves away from SM value, but this is only a 68% CL contour

  16. Conclusions • Very nice electroweak results • Good agreement between two analyses. • Lets go for preliminary at Lepton-Photon 07

  17. CC vs Updated ZEUS-Pol Fit CC e- data with –ve polarisation P= -0.27 Lumi= 78.8 pb-1± 3.5% vs fit predictions for ZEUS-JETS fit including these data CC e- data with +ve polarisation P= 0.33 Lumi=42.7pb-1 ± 3.5% vs fit predictions for ZEUS-JETS fit including these data

  18. a,v-free vs a,v-fixed Team 2 analysis check (ZMVFN) PDFs are stable with free/fixed EW parameters.

  19. ZMVFN scheme 4-EW parameter contours from Team-2 (ZJ and ZO)

  20. ZMVFN scheme 2-EW parameter contours from Team-2 (ZJ and ZO) These 2-EW parameter contours can be compared with those issued in 2006. they are compatible but not identical

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