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Report on fitting FINAL new e-p HERA-II data: - PowerPoint PPT Presentation


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ZEUS fits-Prel. requests for DIS2009 April 21 st 2009 A.M.Cooper-Sarkar and C. Gwenlan. Report on fitting FINAL new e-p HERA-II data: e- CC (175pb -1 : P=0.30, 71pb -1 , P=-0.27, 104pb -1 )(DESY-08-177) e- NC (169pb -1 , P=+0.29, 71pb -1 , P=-0.27, 99pb -1 )(DESY-08-202)

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Report on fitting FINAL new e-p HERA-II data:


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    1. ZEUS fits-Prel. requests for DIS2009 April 21st 2009 A.M.Cooper-Sarkar and C. Gwenlan • Report on fitting FINAL new e-p HERA-II data: • e- CC (175pb-1: P=0.30, 71pb-1, P=-0.27, 104pb-1)(DESY-08-177) • e- NC (169pb-1, P=+0.29, 71pb-1, P=-0.27, 99pb-1)(DESY-08-202) • Then add prel. CC e+p data (134pb-1: P=0.32, 78pb-1, P=-0.36, 56pb-1) • Then add NC e+p data from dedicated ‘FL’ runs at different beam energies HER(Ep=920, 44.5pb-1), MER(Ep=575, 7.1pb-1), LER(Ep=460, 14.0pb-1) (DESY-09-046) • Improvement to PDF uncertainties • Electroweak parameter fit: just MW

    2. ZEUS-JETS NLO QCD fit Eur.Phys.C42(2005)1 Data: Parameterisation: •  parameter constraints: •  momentum and quark number sum rules •  low-x behaviour of uv and dv set equal •  flavour structure of light quark sea set • consistent with Gottfried sum and Drell-Yan •  heavy quarks treated in variable flavour • number scheme of Thorne and Roberts • *Correlated systematic errors treated by OFFSET method We are using the same formalism as the published ZEUS-JETS fit to assess the impact of the new data.

    3. Adding New NC and CCe- data to ZEUS-JETS fit → used to call this the ZEUS-pol when we showed this with preliminary e- data - we need to find a new name This takes the 577 data points of ZEUS-JETS up to 828 data points NC e- 05-06 (final) CC e- 04-06 (final) Prel. requests

    4. Alternatively CC e- 04-06 (final)

    5. Alternatively NC e- 05-06 (final)

    6. Adding New NC and CCe- data to ZEUS-JETS fit Prel. request This takes the 577 data points of ZEUS-JETS up to 828 data points Quadratic 2 PDFs from the new fit compared to published ZEUS-JETS fit – central values of the PDFs do not change much…..

    7. Prel. request The d-flavour sector is less well known- NOTE the scale difference- Hence we look forward to CCe+ data …. The xuv PDF uncertainties are reduced at high-x….. as expected since NC and CC e- cross-sections are both u dominated

    8. Check analysis from Shima – colour coding reversed! Claire and Mandy Shima

    9. Adding New preliminary CCe+ 06-07 data to the previous fit This takes 828 data points up to 898 data points Prel. request

    10. Alternatively CC e+ 06-07 (prel.)

    11. Adding New CCe+ 06-07 preliminary data to previous fit Prel. request This takes 828 data points up to 898 data points Quadratic 2 PDFs from the new fit compared to ZEUS-pol fit – central values of d-valence shift a little…..

    12. Prel. request The d-flavour sector is improved with the addition of CCe+ data The xdv PDF uncertainties are reduced at high-x….. as expected since CC e+ cross-sections are d dominated

    13. Check analysis from Shima – colour coding reversed! Claire and Mandy Shima

    14. Now let’s see the effect of adding everything all at once! ZEUS-HERA-II PDF fit including new NC e- and CC e- data and prel. CC e+ data compared to ZEUS –JETS PDF fit Prel. requests

    15. 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 Prel. Request ?? Should we update our MW value? – well its 2 std.dev. off SM

    16. Adding NC e+ data from HER, MER, LER running to the previous ZEUS-HERA-II fit This takes 898 data points up to 1060 data points Prel. request

    17. Alternatively NC e+p HER/MER/LER vs. fit including that data

    18. Adding NC e+ data from HER, MER, LER running to the previous ZEUS-HERA-II fit Prel. request This takes 898 data points up to 1060 data points Quadratic 2 PDFs from the new fit compared to previous ZEUS-HERA-II fit – central value of gluon shifts a little…..

    19. Prel. Request? The sea and gluon PDF uncertainties are reduced at low-x….. But the mid-x gluon uncertainty expands- this can always happen with the OFFSET method

    20. Prel. Request? The message maybe clearer with expanded low-x scales..

    21. Check analysis from Shima – colour coding reversed! Claire and Mandy Shima

    22. Prel. Request? An alternative way to make the message clearer is to add systematic and statistical errors in quadrature rather than use the OFFSET method.

    23. Summary • We have now repeated our preliminary work of Summer 2007 using the FINAL e- CC and NC data – message: high-x u-valence PDF uncertainties are improved • We have added the preliminary CCe+ data – message: high-x d-valence PDF uncertainties are improved • It is possible to update our MW value • We have added the HER, MER, LER, ‘FL’ data – message: the low-x sea and gluon are improved

    24. Other plots