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:
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=
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=
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= Lumi= 78.8 pb-1 ±3.5%
New NC e- data with +ve polarisation P= Lumi=42.7pb-1 ±3.5%
vs fit predictions from ZEUS-JETS fit including these data

4. Data set
χ2/n.d.p
n.d.p.
CC P-
0.79 37
CC P+
0.85 33
NC P-
0.94 90
NC P+
1.06
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
79.1 ± 0.77 ± 0.99
79.1 ± 0.80 ± 0.97
79.1 ± 0.82 ± 0.98
77.6 ± 1.4 ± 2.5
78.9 ± 2.0(stat) ± 1.8 (sys) (PDF)
82.87 ± 1.82(exp) (model)
ZEUS-jets RTVFN plus new NC/CC e- polarised data ZEUs-only ZMVFN plus new NC/CC e- polarised data
Team-2 value Zeus-only ZMVFN
ZEUS HERA-I data done by this EW+PDF fit method
ZEUS DESY published HERA-I result
H1 HERA-I data done by EW+PDF method
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 MW remember GF SM= ×10-5
Or we can fit a more general formalism: fit g and MW in g2 / (Q2 + MW2)2
such that g2=GF2 MW4 = for standard model,
GF=1.127 ± ± ×10-5 GF=1.123 ± ± ×10-5 GF=1.122 ± ± ×10-5
MW=82.8 ± 1.5 ± 1.3 MW=83.1 ± 1.5 ± 1.2 MW=83.3 ± 1.6 ± 1.0
g= ± ±
g= ± ±
g= ± ±
MW=82.8 ± 1.5 ± 1.3 MW=83.1 ± 1.5 ± 1.1 MW=83.2 ± 1.6 ± 1.0
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= i Bi0(Q2) [xqi(x,Q2) - xqi(x,Q2)]
Ai0(Q2) = ei2 – 2 ei vi ve PZ + (ve2+ae2)(vi2+ai2) PZ2
Bi0(Q2) = – 2 ei ai ae PZ ai 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 = i AiP(Q2) [xqi(x,Q2) + xqi(x,Q2)]
xF3P= i BiP(Q2) [xqi(x,Q2) - xqi(x,Q2)]
AiP(Q2) = 2 ei vi ae PZ - 2 ve ae (vi2+ai2) PZ2
BiP(Q2) = 2 ei ai ve PZ 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. au ad vu vd 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 au ad vu vd
SM value
0.5
-0.5
0.196
0.346
2 EW param.
0.50±0.04±0.09
0.19±0.06±0.06
2 EW param
-0.49±0.14±0.28
-0.37±0.14±0.16
0.48±0.06±0.10
-0.55±0.10±0.21
0.12±0.10±0.05
-0.47±0.15±0.19
3 EW param
0.49±0.03±0.07
ad=-au
0.12±0.10±0.06
-0.48±0.15±0.18
4 EW param
0.59±0.18±0.44
-0.10±0.70±1.73
0.10±0.12±0.22
-0.55±0.20±0.51
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 Tableau ad vu vd
SM value
0.5
-0.5
0.196
0.346
2 EW param.
0.51±0.04±0.09
0.18±0.06±0.05
2 EW param
-0.55±0.13±0.22
-0.32±0.14±0.13
0.51±0.07±0.11
-0.51±0.17±0.24
0.13±0.10±0.04
-0.45±0.15±0.19
3 EW param
0.51±0.03±0.09
ad=-au
0.13±0.11±0.05
-0.44±0.17±0.18
4 EW param
0.64±0.15±0.19
0.04±0.61±1.01
0.13±0.17±0.22
-0.47±0.39±0.65

15. au ad vu vd Team-2 analysis values SM value 0.5 -0.5 0.196 0.346
2 param.
0.52±0.04±0.09
0.18±0.06±0.06
-0.56±0.13±0.23
-0.33±0.14±0.14
0.51±0.07±0.12
-0.52±0.17±0.24
0.13±0.10±0.05
-0.46±0.15±0.19
3 param
0.51±0.03±0.08
ad=-au
0.14±0.11±0.07
-0.43±0.18±0.21
4 param
0.66±0.12±0.12
0.09±0.53±0.73
0.14±0.17±0.20
-0.44±0.40±0.61
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. For further comment on au/ad see Team 2 analysis- next slide
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
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
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. And BSM formalism ai = T3iL-T3iR , vi = T3iL+T3iR – 2ei sin2ƏW
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 ZMVFN Team-2 values in this colour
T3uL
T3dL
T3uR
T3dR
sin2ƏW
0.47±0.05±0.13
0.50±0.06± ±0.06±0.13 SM formalism
-0.55±0.18±0.35
-0.53±0.19± ±0.22±0.42
0.231±0.024±0.070
0.234±0.024±0.061
0.229±0.017±0.071
0.5
BSM :2 EW param fit
-0.5
-0.05±0.05± ±0.05±0.11
-0.14±0.15± ±0.14±0.25
0.2315
BSM:3 EW param fit
-0.07±0.07±0.07
-0.08±0.07±0.05
-0.26±0.19±0.19
-0.22±0.21±0.13
0.238±0.011±0.023
0.236±0.012±0.020

23. Team-2 version of T3u/T3d contour
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
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 fit also shown compared to the H1 contour

26. Contours from the T3uR / T3dR/ sin2ƏW 3-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. H1 4-parameter contours, ZEUS-4 parameter from HERA-I
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