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