ZEUS fitsPrel requests for DIS 2009 April 21

ZEUS fits-Prel. requests for DIS 2009 April 21 st 2009 A. M. Cooper-Sarkar and C. Gwenlan • Report on fitting FINAL new e-p HERA-II data: • e- CC (175 pb-1: P=0. 30, 71 pb-1, P=-0. 27, 104 pb-1)(DESY-08 -177) • e- NC (169 pb-1, P=+0. 29, 71 pb-1, P=-0. 27, 99 pb-1)(DESY-08 -202) • Then add prel. CC e+p data (134 pb-1: P=0. 32, 78 pb-1, P=-0. 36, 56 pb-1) • Then add NC e+p data from dedicated ‘FL’ runs at different beam energies HER(Ep=920, 44. 5 pb-1), MER(Ep=575, 7. 1 pb-1), LER(Ep=460, 14. 0 pb-1) (DESY-09 -046) • Improvement to PDF uncertainties • Electroweak parameter fit: just MW

ZEUS-JETS NLO QCD fit Eur. Phys. C 42(2005)1 Data: all HERA-I ZEUS incl. NC/CC e+/e- (94 -00) ZEUS inclusive jets in DIS (96 -97) ZEUS dijets in photoproduction (96 -97) Parameterisation: PDF Param. at Q 02 =7 Ge. V 2 u-val. (xuv) Auv xbuv (1 -x)cuv (1+duvx) d-val. (xdv) Adv xbdv (1 -x)cdv (1+ddvx) total sea (x. S) AS xb. S (1 -x)c. S gluon (xg) Ag xbg (1 -x)cg (1+dgx) dbar-ubar (x ) A xb (1 -x)c 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.

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) Prel. requests CC e- 04 -06 (final)

Alternatively CC e- 04 -06 (final)

Alternatively NC e- 05 -06 (final)

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 Dataset 2/ndp CC e-p P=- 1. 39 37 CC e-p P=+ 0. 97 34 NC e-p P=- 1. 00 90 NC e-p P=+ 0. 95 90 PDFs from the new fit compared to published ZEUS-JETS fit – central values of the PDFs do not change much…. .

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

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

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

Alternatively CC e+ 06 -07 (prel. )

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…. . Dataset 2/ndp CC e-p P=- 1. 43 37 CC e-p P=+ 0. 99 34 NC e-p P=- 1. 00 90 NC e-p P=+ 0. 95 90 CC e+p P=- 0. 80 35 CC e+p P=+ 1. 25 35

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

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

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

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 GF 2 MW 4/(Q 2+MW 2)2 Value of MW (=80. 4 SM) 78. 0 ± 1. 2(exp) Prel. Request ? ? 77. 6 ± 2. 9(exp) 78. 9± 2. 0(exp)± 1. 8+2. 2 -1. 8(PDF) 82. 87 ± 1. 82(exp) +0. 32 Specifications of the fit ZEUS-jets RTVFN including NEW CC/NC e-data and NEW preliminary CC e+ data ZEUS HERA-I data done by this method (unpublished) ZEUS DESY-03 -093 fit to dσ/d. Q 2 data (published) H 1 HERA-I data done by this method 0. 16(model) Should we update our MW value? – well its 2 std. dev. off SM

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

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

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 Dataset 2/ndp CC e-p P=- 1. 43 37 CC e-p P=+ 0. 99 34 NC e-p P=- 1. 00 90 NC e-p P=+ 0. 95 90 CC e+p P=- 0. 80 35 CC e+p P=+ 1. 25 35 LER 0. 84 54 MER 0. 73 54 HER 0. 97 54 PDFs from the new fit compared to previous ZEUS-HERA-II fit – central value of gluon shifts a little…. .

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

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

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

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.

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

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