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Electroweak Parameter Fits Report Request

charlize-vaughn avatar
charlize-vaughn
30 diapositives · 414 Views · Nov 21, 2014

Requesting preliminary data analysis including improvement in PDF uncertainties, electroweak parameter fits with new CC and NC polarised data. Comparison of preliminary PDFs and reductions in uncertainties for high scales. Analysis of MW as a free fit parameter and MW entering the factor GF2.MW4/(Q2+MW2)2. Fits to electroweak NC couplings and new polarised datasets. Team-2 analysis of 2 and 3 EW parameter values. Contours comparison and exploration of vu/vd and au/ad in polarised data for further insights.

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  1. ZEUS fits-report request for preliminary April 3rd 2006 A.M.Cooper-Sarkar and C. Gwenlan – team-1 K.Nagano and S. Shimizu – team -2 Web page:http://www-pnp.physics.ox.ac.uk/~cooper/polarised/ewfit.html • Report on fitting new data on e- CC and NC polarised • Improvement to PDF uncertainties • Electroweak parameter fits: MW , MW/ GF ,MW/ g • Electroweak NC couplings: au ad vu vd and T3uL/R, T3dL/R sin2ƏW

  2. Including the new data in the standard PDF fit formalism Request preliminary New CC e- data with –ve polarisation P= -0.268297 Lumi= 78.8 pb-1 ±3.5% vs fit predictions for ZEUS-JETS fit including these data New CC e- data with +ve polarisation P= 0.328555 Lumi=42.7pb-1 ±3.5% vs fit predictions for ZEUS-JETS fit including these data

  3. Request preliminary New NC e- data with –ve polarisation P= -0.268297 Lumi= 78.8 pb-1 ±3.5% New NC e- data with +ve polarisation P= +0.328555 Lumi=42.7pb-1 ±3.5% vs fit predictions from ZEUS-JETS fit including these data

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

  5. Team 2 analysis check

  6. 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

  7. Request preliminary Improvement in uncertainty remains up to high scales- important for LHC physics!

  8. Team-2 analysis

  9. Electroweak parameter fits Now let MW be a free parameter of the fit, together with the PDF parameters How does MW enter the fit? In the factor GF2 MW4/(Q2+MW2)2 Value of MW (=80.4 SM) Specifications of the fit Request preliminary Note model dependence is small because there is little correlation between EW and QCD sector of the fit

  10. Request preliminary values in this colour Zeus-jets RTVFN Check with ZEUS-only ZMVFN Team 2 analysis values in this colour Can also fit BOTH GF and MWremember GF SM= 1.11639×10-5 Or we can fit a more general formalism: fit g and MW in g2 / (Q2 + MW2)2 such that g2=GF2 MW4 = 0.07542 for standard model, This is the most general way to present our data

  11. Now consider fits to electroweak NC couplings as well as PDF parameters At LO the NC unpolarised structure functions are given by F20= i Ai0(Q2) [xqi(x,Q2) + xqi(x,Q2)] xF30= iBi0(Q2) [xqi(x,Q2) - xqi(x,Q2)] Ai0(Q2) = ei2 – 2 eivi vePZ + (ve2+ae2)(vi2+ai2) PZ2 Bi0(Q2) = – 2 eiai ae PZ + 4ai ae vi ve PZ2 PZ2 = Q2/(Q2 + M2Z) 1/sin2θW And the unpolarised cross-section is given by σ0 = Y+ F20 + Y- xF30 The polarised structure functions are given by F2P = iAiP(Q2) [xqi(x,Q2) + xqi(x,Q2)] xF3P= i BiP(Q2) [xqi(x,Q2) - xqi(x,Q2)] AiP(Q2) = 2 eivi ae PZ - 2 ve ae (vi2+ai2) PZ2 BiP(Q2) = 2 eiai ve PZ - 2 ai vi (ve2+ae2) PZ2 and the polarised cross-section is given by σP = Y+ F2P + Y- xF3P So that the total cross-section is given by σ = σ0 + P σP Given that ve is very small and that the γ/Z interference terms in PZ dominate the PZ2 terms, we can see that infromation on au, ad comes from unpolarised xF30 and infromation on vu,vd comes from polarised F2P

  12. SM formalism ai = T3i , vi = T3i – 2ei sin2ƏW Let ai and vi be free as well as PDFparameters. Perform fits with 2, 3 or 4 EW parameters free Request preliminary on 2 and 3 EW parameter values The 4- parameter fit has fallen foul of a double minimum- (which was avoided by pure luck with the earlier collab. meeting version of the data)- see later

  13. New 4-parameter fit contours compared to: H1 4-parameter contours,ZEUS-4 parameter from HERA-I and to what we thought we had got from new data at the time of the collaboration meeting au/vu contour is not so different and is much better than without polarised data The ad/vd contour is a somwehat different shape and more extended in ad, BUT still a substantial improvement in vd when compared to HERA-I data

  14. ZEUS-only ZMVFN version of previous Table

  15. Team-2 analysis values Excellent agreeent of 2 and 3 parameter values, good agreement of 4-parameter values..but note the fit is unstable for 4-parameters because of the double minimum, so small differences get magnified

  16. Request preliminary for these 2-EW parameter contours Team- 2 contours for 2-EW parameter fits

  17. Comparison of 2EW parameter contours with those of H1, and with LEP and CDF results

  18. Alternative 2-EW parameter contours, reflecting how our data access au/ad in XF30(unpolarised) and vu/vd in F2P(polarised) Request preliminary for vu/vd, this exploits the information in new polarised data For further comment on au/ad see Team 2 analysis- next slide

  19. Team 2 au/ad and vu/vd 2-parameter contours: Note the double minimum in au/ad space – the central values of 0.51,-0.52 are NOT at the centre of this contour..but in the bottom bulge. There is clearly an alternative minimum at au~0.65, ad~0.1..that is what is found by the 4-parameter fit

  20. Contours from the 3-EW parameter fit just for information. Note this graph is constructed by flipping au in sign to give ad=-au.

  21. Team-2 contours from 3 parameter fit..note this graph should have au flipped in sign to give ad=-au, to make sense of it

  22. Alternative ways to present the NC couplings using SM formalism ai = T3iL , vi = T3iL – 2ei sin2ƏW: And BSM formalism ai = T3iL-T3iR , vi = T3iL+T3iR – 2ei sin2ƏW (note sin2ƏWalso enters the PZ propagator and ve) Request preliminary: values in this table ZEUS-ONLY ZMVFNTeam-2 values in this colour

  23. Request preliminary T3u/T3d contour from the 3-EW parameter SM formalism fit This is essentially an au/ad contour with added constraints from the SM formalism Team-2 version of T3u/T3d contour

  24. Other contours from the T3u/ T3d/ sin2ƏW 3 EW param. SM job for information

  25. Request preliminary the T3uR /T3dR contour from the 2 EW parameter BSM fitalso shown compared to the H1 contour

  26. Contours from the T3uR / T3dR/ sin2ƏW3-EW parameter beyond SM formalism fit for information

  27. Conclusions • Very nice electroweak results • Agreement with 2nd analysis • Lets go for preliminary at DIS06

  28. 4-param fit contours (statistical) only for information

  29. Comparison to: H1 4-parameter contours, ZEUS-4 parameter from HERA-I and to what we thought we had got from new data at the time of the collaboration meeting au/vu contour is not so different and is much better than without polarised data The ad/vd contour is a somwehat different shape and more extended in ad, BUT still a substantial improvement in vd when compared to HERA-I data

  30. Team-2 4parameter contours