•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

ZEUS fits-Prel. requests for DIS2009April 21st 2009

A.M.Cooper-Sarkar and C. Gwenlan

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

PDF Param. at Q02 =7 GeV2

u-val. (xuv) Auv xbuv (1-x)cuv (1+duvx)

d-val. (xdv) Adv xbdv (1-x)cdv (1+ddvx)

total sea (xS) AS xbS (1-x)cS

gluon (xg) Ag xbg (1-x)cg (1+dgx)

dbar-ubar (x) A xb (1-x)c

all HERA-I ZEUS incl. NC/CC e+/e- (94-00)

ZEUS inclusive jets in DIS (96-97)

ZEUS dijets in photoproduction (96-97)

Data:

Parameterisation:

ZEUS-JETS NLO QCD fit Eur.Phys.C42(2005)1

We are using the same formalism as the published ZEUS-JETS fit to assess the impact of the new data.

CC e- 04-06 (final) NC e- 05-06 (final)

This takes the 577 data points of ZEUS-JETS up to 828 data points

Prel. requests

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

Alternatively

CC e- 04-06 (final)

Alternatively

NC e- 05-06 (final)

PDFs from the new fit compared to published

ZEUS-JETS fit – central values of the PDFs do not change much…..

Adding New NC and CCe- data to ZEUS-JETS fit

This takes the 577 data points of ZEUS-JETS up to 828 data points

Dataset 2/ndp 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

Quadratic 2

Prel. request

The xuv PDF uncertainties are reduced at high-x ….. as expected since NC and CC e- cross-sections are both u dominated

The d-flavour sector is less well known- NOTE the scale difference-

Hence we look forward to CCe+ data ….

Prel. request

Claire and Mandy Shima

Check analysis from Shima – colour coding reversed!

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.)

PDFs from the new fit compared to

ZEUS-pol fit – central values of d-valence shift a little…..

Adding New CCe+ 06-07 preliminary data to previous fit

This takes 828 data points up to 898 data points

Dataset 2/ndp 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

Quadratic 2

Prel. request

The xdv PDF uncertainties are reduced at high-x ….. as expected since CC e+ cross-sections are d dominated

The d-flavour sector is improved with the addition of CCe+ data

Prel. request

Check analysis from Shima – colour coding reversed!

Claire and Mandy Shima

ZEUS-HERA-II PDF fit including new NC e- and CC e- data and prel. CC e+ data compared to ZEUS –JETS PDF fit

Now let’s see the effect of adding everything all at once!

Prel. requests

Electroweak parameter fitsNow 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 MW4/(Q2+MW

2)2

78.0 ± 1.2(exp) ZEUS-jets RTVFN including NEW CC/NC e-data and NEW preliminary CC e+ data

77.6 ± 2.9(exp)

78.9± 2.0(exp)±1.8+2.2-1.8(PDF)

82.87 ± 1.82(exp) +0.32 0.16(model)

ZEUS HERA-I data done by this method (unpublished)

ZEUS DESY-03-093 fit to dσ/dQ2 data (published)

H1 HERA-I data done by this method

Value of MW (=80.4 SM) Specifications of the fit

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

Prel. Request ??

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

This takes 898 data points up to 1060 data points

Dataset 2/ndp 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

Quadratic 2

Adding NC e+ data from HER, MER, LER running to the previous ZEUS-HERA-II fit

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?

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

Other plots