Parton Distributions Experiments Introduction Unpolarized Parton Distribution Functions

Parton Distributions, Experiments Introduction Unpolarized Parton Distribution Functions (PDF) Helicty difference PDFs Helicty flip: Transversity EIC Matthias Grosse Perdekamp, RBRC Lightcone 2002, Los Alamos August 6, 2002 Parton Distributions, Experimental

Motivation Explore fundamental structure of matter: Nucleon as laboratory to study QCD o Sum rules o Evolution o o hard scattering Input to the study of Fundamental Interactions at Hadron (or HI) Colliders o Tevatron/LHC o Interpretation of data requires errors… (eg. high x, Q 2 events at HERA, high p. T jets at CDF) August 6, 2002 Parton Distributions, Experimental

Example CDF Inclusive Jet Cross Section vs ET F. Abe, et. al, Phys. Rev. Lett. 77(1996)438 Range of available PDFs does not correctly estimate PDF uncertainties. August 6, 2002 Parton Distributions, Experimental

NLO QCD Fit with Error propagation M. Botje, DIS 2000 using Zeus and H 1 data. August 6, 2002 Parton Distributions, Experimental

CTEQ 6 J. Pumplin et. al JEHP 0207: 012 (2002) New Data Sets: Neutral Current H 1, Zeus, D 0 inclusive jets E 866 Drell/Yan d/p CCFR F 2, re-analyzed Old Data Sets : BCDMS, NMC CCFR F 3, E 605 Drell/Yan CDF: W-lepton asymmetry CDF inclusive jets August 6, 2002 Parton Distributions, Experimental

Channel Overview August 6, 2002 Parton Distributions, Experimental

R. S. Towell et. Al, Phys. Rev. D 64(2001)05002 August 6, 2002 Parton Distributions, Experimental

CTEQ 6 M August 6, 2002 J. Pumplin et. al JEHP 0207: 012 (2002) Parton Distributions, Experimental

CTEQ 6 M Uncertainties J. Pumplin et. al JEHP 0207: 012 (2002) Zeus/H 1 August 6, 2002 D 0 -Jet Parton Distributions, Experimental

CTEQ 6 M vs Experiment J. Pumplin et. al JEHP 0207: 012 (2002) D 0 Jet Cross Section August 6, 2002 Parton Distributions, Experimental

CTEQ 6 M vs Experiment J. Pumplin et. al JEHP 0207: 012 (2002) ZEUS F 2 August 6, 2002 Parton Distributions, Experimental

Uncertainties at the Tevatron II/LHC PDF related uncertainties W, Z 4% August 6, 2002 Higgs 5% Parton Distributions, Experimental

Compare Unpolarized and Polarized Data Sets g 1 F 2 10 August 6, 2002 103 105 Q 2 (Ge. V 2) 1 10 102 Q 2 (Ge. V 2) Parton Distributions, Experimental

Helicity Difference PDFs with Errors J. Blümlein, H. Böttcher, Nucl. Phys. B 636(2002), 225 Gluon Spin Contribution is unknown! August 6, 2002 Parton Distributions, Experimental

Polarized PDFs from SMC QCD Analysis August 6, 2002 Parton Distributions, Experimental

HERMES Results on high p. T Hadron Pairs (theoretical errors unspecified) August 6, 2002 Parton Distributions, Experimental

Scale Dependence of Cross Sections in Gluon Distribution Measurements HERMES (hadron pairs) COMPASS (hadron pairs) E 708 (direct photon) RHIC (direct photon) CDF (direct photon) August 6, 2002 Parton Distributions, Experimental

Measurements Polarized pp Polarized DIS HERMES, COMPASS, E 161, EIC, TESLA-N PHENIX Hadron Production Heavy Flavors Jet Photon August 6, 2002 Single and Di-Jets Photo production of charm and high p. T hadron pairs STAR Direct Photon TESLA-N p. QCD at low x Parton Distributions, Experimental HERMES COMPSASS E 161 STAR, PHENIX EIC Future

Sensitivity of future Gluon Polarization Measurements Plot provided by E. C. Aschenauer August 6, 2002 Parton Distributions, Experimental

Near Future: Inclusive Hadron Asymmetries NLO QCD applicable down to p. T=2 Ge. V! Data vs p. QCD with different factorization scales Scale dependence of p. QCD calculations in channels relevant for measurements: PHENIX vs HERMES and COMPASS HERMES (hadron pairs) 2μ (factorization scale) COMPASS (hadron pairs) μ RHIC PHENIX (direct photon) μ/2 PHENIX (inclusive hadrons) CDF (direct photon) photon August 6, 2002 Statistical errors only Parton Distributions, Experimental

Impact of RHIC ALL Measurement in Incl. Had. Production in 2003 • Comparison of projected PHENIX ALL measurements (200 Ge. V, 3 pb-1) with asymmetries obtained from the GRSV maximal and standard gluon polarization. W. Vogelsang August 6, 2002 Parton Distributions, Experimental

The first RHIC Polarized Proton Run • New detector components • Integrated Luminosity August 6, 2002 Parton Distributions, Experimental

Projected Statistical Error for AN Measurement • 10 x precision of previous best measurement (E 704) • High p. T at midrapidity permits p. QCD interpretation – Bounds on the product of transversity quark distributions and the Collins Heppelman fragmentation function. August 6, 2002 Parton Distributions, Experimental

Transversity Distributions Hard Scattering Amplitudes probe On Transversity: Transversity distributions remain last unmeasured leading twist distributions does not mix with gluons under evolution Incoming proton First lattice QCD result: S. Aoki, M. Doui, T. Hatsuda and Y. Kuramashi Phys. Rev. D 56 (1997)433 More recently: S. Capitani et. al. Nucl. Phys. B (Proc. Suppl. ) 79 (1999) 548 Access to transversity distributions: (helicity flip!) August 6, 2002 Parton Distributions, Experimental

Avenues to Transversity Polarized pp Polarized DIS RHIC/BNL HERA/DESY, SPS/CERN, EIC, TESLA-N August 6, 2002 HERME S COMPAS S TESLAN EIC PHENIX STAR (Approved Transversity Programs) Parton Distributions, Experimental

Drell Yan at RHIC J. Ralston and D. E. Soper, Nucl. Phys. B 152, 109(1979) O. Martin, A. Schafer, M. Stratmann, W. Vogelsang Phys. Rev. D 60, 117502(1999) August 6, 2002 Parton Distributions, Experimental

CHF at HERMES August 6, 2002 Parton Distributions, Experimental

TESLA-N 250 Ge. V electrons on polarized fixed targets, 100 fb-1 August 6, 2002 Parton Distributions, Experimental

TESLA-N: Interference Fragmentation August 6, 2002 Parton Distributions, Experimental

Collins Effect at EIC August 6, 2002 Projected errors on A in 5 z- bins Parton Distributions, Experimental

EIC kinematic coverage X-Q 2 Coverage of the present DIS facilities shown in comparison to a Electron Ion Collider (EIC): Ep=50 -250 Ge. V, Ee=5 -10 Ge. V Fixed target muon DIS Fixed target electron DIS it c ati DIS A R E ki m ne For e-A Unpolarized “low x” means For lim For Polarized e-p “low x” means lower than SMC measured x: H PHOTOPRODUCTION August 6, 2002 EIC LARGE LUMINOSITY Parton Distributions, Experimental

Nuclear effects in nucleon structure E 665, NMC & SLAC Collaborations F 2 D/F 2 A Low Q 2! • • • Fermi motion EMC effect Enhancement Shadowing Saturation? Region of Shadowing and saturation hardly have data with Q 2> 1 Ge. V 2 An e-A Collider will measure these regions! August 6, 2002 Parton Distributions, Experimental

Statistical Precision possible with EIC T. Sloan EIC 1 inv. pb August 6, 2002 Statistical Precision Possible with EIC: • NMC data F 2(Ca/D) • EIC data with L=1 inv. pb • Also extends the measurements in to the low x region keeping the Q 2>1 Ge. V 2! • Region of saturation? color glass condensate? Parton Distributions, Experimental

Result of Di-Jet analysis at NLO G. Radel & A. De Roeck, A. Deshpande, V. Hughes, J. Lichtenstadt Statistical accuracy shown for EIC (HE) for 2 luminosities Detector smearing effects studied NLO analysis for Di-Jet Included • • Easy to differentiate between different scenarios of DG: Improves DG by factor of ~3 Combined analysis: Di-Jet + p. QCD analysis of g 1: DG constrained by these two together further improves the uncertainties by additonal factor of ~3 Effectively factors of 10 impovement in DG can be expected! August 6, 2002 Parton Distributions, Experimental

Parity Violating Structure Functions g 5 • Unique measurement with EIC (HE) • Identified by missing neutrino momentum: huge asymmetry in detector • Complementary measurement to RHIC SPIN August 6, 2002 In EIC (HE) kinematics Parton Distributions, Experimental

Measurement Accuracy PV g 5 with EIC J. Contreras et al. Assume: 1) Input GRV Polarized PDFs 2) x. F 3 is measured well by that time 3) 4 fb-1 luminosity (~1. 5 months run) If e+ and e- possible then one can have g 5(+) as well. Separate flavors Delta u, Delta d etc. August 6, 2002 Parton Distributions, Experimental

A Case for EIC • Explore an absolutely new regime of QCD: An e-A collider will provide a unique opportunity to explore fundamental and universal aspects of QCD. • Measurements would be essential to fully understand the QGP already being studied at RHIC now, also physics at LHC later. • An e-A collider will also allow us to explore with great precision inclusive measurements that have not been pursued beyond the fixed target experimental era. It would also enable, for the first time, a wide range of semi-inclusive measurements in a nuclear environment. August 6, 2002 Parton Distributions, Experimental

A Case for EIC (cont. )…. . • A polarized e-p scattering facility with variable sqrt(s) will allow a) at high sqrt(s) a new region in the x-Q 2 to be explored for the spin DIS. It will address issues that no other present or future approved facility will address. b) in the already measured x-Q 2 range the high luminosity of EIC will allow us to settle lots of yet uncertain issues regarding the proton spin! • Detector and its surrounding experimental area, details of the accelerator design: To_Do! • If the facility is built at BNL, RHIC will become a unique facility where particle & nuclear physicists can do experiments of their choice: e-A. , e-p, polarized e-p, p-A, polarized p-p, A-A. August 6, 2002 Parton Distributions, Experimental

Polarized Collider : RHIC p. C Polarimeters BRAHMS & PP 2 PP (p) Absolute Polarimeter (H jet) PHENIX (p) STAR (p) Spin Rotators Partial Siberian Snake LINAC BOOSTER Pol. Proton Source 500 m. A, 300 ms 200 Me. V Polarimeter August 6, 2002 Siberian Snakes 2 1011 Pol. Protons / Bunch e = 20 p mm mrad AGS Internal Polarimeter Rf Dipoles Parton Distributions, Experimental

Conclusions Quality of PDFs permits quantitative predictions with solid errors of Tevatron II and LHC physics. Many open questions at hard scales: A-dependence, saturation, flavor structure, spin structure, transversity, semi-inclusive and exclusive processes. New facilities: HERMES, COMPASS, SLAC, Jefferson Lab, RHIC spin with exciting possibilities in the near future. August 6, 2002 Parton Distributions, Experimental