10.9.2002 MK @RADCOR02

Structure Functions at HERA Max Klein (H1, DESY Zeuthen)

Status and Future

RADCOR 02 Kloster Banz 10.9.2002

-Introduction-F2 at Low x-Measurement of alphas and xg-High Q2 -Quark Distributions-FL now and then-Summaryno jets, spin

klein@ifh.de

10.9.2002 MK @RADCOR02

HERA

ZEUS H1 positrons

positrons

protons

protons

HERA -tunnel

protons: 920 GeV positrons: 27.5 GeV

circumference: 6.3 km

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1992

introduction

1997

luminosity 0.2 20 pb-1detector upgrades

uncertainty 20% 2-3%

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deep inelastic scattering at low x and Q2

most recent, 0.6pb-1H1 DIS 02 Cracow

low x

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kinematic reconstruction

BST BST SPACAL

low x

preliminary (H1) small photoproduction bgd: E-pz, BST track

10.9.2002 MK @RADCOR02 low x

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reduced cross section

y<0.8

low x

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Fractal Proton Structure – Self Similarity

log dependence of (unintegrated parton) density

fit to H197 low Q2 data and to ZEUS 97 BPT

T.Lastovicka hep-ph/0203260 EPJ in print

4.1382 for 172 points, D2=1

low x

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QCD below its applicability

low x

ZEUS hep-ex/0208023

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rise towards x0

should have lowered Ee

low x

derivative independent of xfor x<0.01 to within exp uncertainty

PhysLett B520(01)183

H1 preliminary, DIS02, svx data 2000

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PhysLett B520(01)183

derivative ~ lnQ2

still higheraccuracy desirable

low x

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exploring perturbative QCD

xgQF

s 2

2

ln

alphas

H1 EPJ C21(01)33

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determination of the gluon momentum density to NLO

H1 EPJ C21(01)33

fixed flavour nr schemeLaenen, Riemersma, Smith, vanNeerven

need precision data at low Q2, all x!

alphas

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DIS measurement of alphas with H1 and BCDMS data

alphas

y(BCDMS) > 0.3Q2(BCDMS) >7 GeV2

no NMC, E665chi2+1 well defined

is BCDMS correct? low Ep run H1 EPJ C21(01)33

joint determination of alphas, xg, V,A

F2 =xV/3 +11xA/9 = 4xU/9+xD/9

xg ~xbg

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Results on the strong coupling constant

hep-ex/0208023

alphas

EPJ C21(01)33

•H1

0.1150 +-0.0017(exp)+0.0009-0.0007(model)if: systematíc errors are not fitted: +0.0005 NMC replaces BCDMS 0.116+-0.003 (exp) 4 light flavours: +0.0003 BCDMS deuteron data added: 0.1158 +- 0.0016 (exp)

large chi2 variations if Q2 (¼ .. 4) Q2 renormalisation scale:+-0.005 (H1)

(1/2.. 2) : +- 0.004 (ZEUS) not included in error

•ZEUS 0.1166 +-0.0008(unc)+-0.0032(corr)+-0.0036(norm)+-0.0018(model)

p:BCDMS,NMC,E665 d:NMC,E665 d/p: NMC xF3: CCFRsystematíc errors are not allowed to vary in chi2 minimisationQ2>2.5 GeV2, W2>20GeV2, RTvfns, b(uv)=1/2, b(dv)=1/2fit alphas, xg, uv, dv, sea, dbar-ubar (MRST)if fixed flavour scheme is used: +0.0010

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electroweak unification in DIS

K.Long ICHEP02

high Q2

full data 1994-2000

10.9.2002 MK @RADCOR02 ICHEP02 H1 preliminary high Q2

10.9.2002 MK @RADCOR02 ICHEP02 H1 preliminary high Q2

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neutral currents at high x,Q2

high Q2

HERA 2

high Q2 simulationNC uncertainty ~2%CC uncertainty ~3%

A.Mehta DIS01

HERA2: 10 times the luminosity of HERA1

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exploratory measurements of xF3

32

33 2 xHavxGaxF ZeeZe

H1: EPJ C19(2001)269; ZEUS: hep-ex/0208040

high Q2

]2[)]()([23 vvdduu duxddaeuuaexxG direct access to valence quarksparity conserving

e+ 100 pb-1 e- 15 pb-1

requires maximum possible luminosity

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hep-ex/0208023.

high Q2 CC data (ZEUS)

high Q2

CC data not fitted

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ICHEP02 prel.

high Q2 CC data (H1)

high Q2

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MK high x Philadelphia 00

pdf

e+, 250pb-1

e-, 250pb-1

simulation HERA2

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A.Mehta DIS01.

CC polarisation dependence

high Q2

search for r.h. currents

classic measurement, possiblewith modest luminosity but maximum polarisation

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parity violation in F2 (gamma-Z)

MK DIS01 Bologna

high Q2

)(9/2)(2

)4/()(/

2

122

qqxqqvexG

ududFGaA

qq

vvvvZx

eZ

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parton distribution functions from NLO QCD fits

ZEUS hep-ex/0208023; H1 ICHEP02

pdf

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parton distribution functions from NLO QCD fits (H1)

H1 ICHEP02

pdf

CC and NC cross sectionsare sensitive only to U, antiU, D,antiD

(F2N has c-s admixture)

new H1 NLO QCD fitin which uv,dv,sea arereplaced by the observables

light flavours (xg consistent)

possible with H1 data alonewith assumption on sea symmetry

10.9.2002 MK @RADCOR02

sea symmetry (simulation of ed)

MK, DIS 02

pdf

40pb-1 ep 20pb-1 ed

note (s-c)/3 =5/18 W2(cc)-F2N

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up and down quarks at high Q2

ZEUS hep-ex/0208023; H1 ICHEP02

pdf

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access to the longitudinal structure function

FL

H1 EPJ C21(01)33

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determination of the longitudinal structure function

FL

H1: EPJ C21(01)33, DIS01 and ICHEP02

y<0.9(this is E‘~2..3 GeV!)

assumption on F2

more accurate dataat large Q2 to come

consistent with NLO QCDi.e. scaling violations of F2

limited to smallest x

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FL simulation with lowered Ep

FL

MK Ringberg H1 internal 02: bins and Ep choices may be optimised

3..4 beam energiesL ~ Epsystematics challengesmallest E‘ (BST: E/p)ultimate accuracy of ~5%Q2~1 GeV2: redo i.a.region

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F2 charm

FL

ICHEP02

beauty to follow

Silicon detectors vital

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diffractive partons

FL

H1, DIS02

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summary+Low x physics discovered as a new field of theoretical development and experimental fun+ so far pQCD is consistent with structure function data but the ultimate precision of data and thy (N3LO) is still to be / is being approached (F2 1%, FL 5%, hiQ2 2% NC, 3% CC, about!)+ F2c and F2D evolve towards precision testing grounds

HERA1

HERA2

HERA3

+ high luminosity, Silicon detectors, improved calibrations large x, high Q2 (competetive searches)+ NC,CC unfold pdf‘s, employ polarisation and charge dependence of cross sections, xg at high x??+ high accuracy, low Ep runs determine strong coupling constant with 1% accuracy and measure FL(x)

+ explore flavour decomposition at low x (eD)+ discover saturation (eA)+ understand confinement (better)+ spin structure of the proton at low x and high Q2

10.9.2002 MK @RADCOR02

ZEUS upgrades

ZEUS expected to be operational in 2006 (U.Schneekloth at Durham)

STT MVD new beam pipe

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H1 upgrades

major upgrades. H1 expected to be operational for years to come and follow – design 1986!

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Workshops

•its time to conclude

•DESY directorate asks for proposals by end of 2003

•Physics•Ressources•TESLA•synch.radiation

10.9.2002 MK @RADCOR02