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Summay of Session 2 QCD spin structure of nucleons

Summay of Session 2 QCD spin structure of nucleons. Summary Session 2. Introduction Helicity distributions Gluon polarisation transversity. Summary of Session 2. six excellent plenary talks: Metz, Barone, Garçon, Hasch, Bressan, Saito 55 talks in parallel sessions, 16 h

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Summay of Session 2 QCD spin structure of nucleons

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  1. Summay of Session 2 QCD spin structure of nucleons

  2. Summary Session 2 Introduction Helicity distributions Gluon polarisation transversity

  3. Summary of Session 2 • six excellent plenary talks: Metz, Barone, Garçon, Hasch, Bressan, Saito • 55 talks in parallel sessions, 16 h • half experiment / half theory • exp. talks: about 2/3 ℓp, 1/3 pp • theo. talks: about 1/3 on transversity and SSA Apologies for not being able to cover everything appropriately

  4. HELICITY DISTRIBUTIONS

  5. Final g1 for p, d, n Riedl • quasifinal data set for p and d • corrected for smearing (radcor, detector)

  6. Quark helicity distributions Rubin

  7. Inclusive asymmetries Peshekhonov inclusive • COMPASS deuteron data 2002 – 2003 • most precise data for x<3x10-2 • 2004 similar precision • kaon/pion asymmetries to come +vehadrons

  8. Δq - Theory • method using A and moments to determine • model-independent determination of from incl. and semi-incl. asym. in LO and NLO. Fragmentations functions cancel in needs very precise data (Jlab) Shevchenko Christova remark: A exp. diffcult with magnetic spectrometers

  9. Δq - JLAB Jiang • under construction (2006-2007) • expect very precise data for x > 0.1 • apply method Semi-SANE E04-113

  10. Evolution • role of higher twist in the determination of PDF. HT cancels largely in A1 . • small-x evolution:double logarithm resummation important forg1for x ≤ 10-3 -10-4 Stamenov Ermolaev • parametrisation-independent matrix solution of DGLAP • estimates of ΔG/G and Lqranges Goshtasbpour Ramsey

  11. GLUON POLARISATION

  12. ΔG/G - Photon-Gluon Fusion measured aLL: calculable partonic asymmetries R: Monte-Carlo (Lepto for Q2 > 1 GeV2)

  13. ΔG/G - SMC Rondio • event selection high-pT pairs • Q2 > 1 GeV2 • neural network • ΣpT2 > 2.5 GeV2 • RPGF = 0.32 Hermes (all Q2) SMC pT12+pT22 NN xg

  14. ΔG/G - COMPASS Schill • Analysis a la SMC • ΣpT2 > 2.5 GeV2, Q2 > 1 GeV2 • open charm signal 10% of statistics 2002/3 PGF: cc open charm Hermes Compass 2002/3 SMC

  15. ΔG/G – RHIC pp π0

  16. ΔG/G - Phenix: ALL for π0 Fukao 2003/4 Outlook 2005/7

  17. ΔG/G – Star: ALL jets (2005) 1.0 Inclusive Jets :LO W. Vogelsang 0.8 STAR qg 0.6 0.4 gg qq 0.2 0.0 0 5 10 15 20 25 30 Sowinski 2005 pT (GeV)

  18. NLO and NLL Vogelsang • Resummation of NLL important for single-inclusive processes ( , ) • Crucial for lower energy fixed target • Excellent agreement of NLO + NNL calculations with collider data! • prompt photons good probe for ΔG/G at RHIC

  19. Prompt photons/π0 π0 prompt γ Vogelsang, Okada

  20. RHIC detector upgrades GS95 prompt photon central arms NCC • important enlargement ofxgcoverage  first moment Tungsten-Silicon sampling calorimeter Kinney Togawa Silicon vertex barrel detector 2009 2007-2008

  21. Proposals • Spintransfer in Hyperon production in pp Xu, Rykov • Polarised DY p↑ p↑at GSI (transversity) Efremov

  22. TRANSVERSE SPIN

  23. AN for pp -> π0X STAR Makdisi Ogawa xF = 0

  24. SSA andintrinsic kT Murgia, D’Alesio • A generalized pQCD approach to SSA and unpol. cross sections: LO.pQCD + spin and new kT-dependent PDF and FF • AN (p↑pπX): • Sivers effect contributes, Collins effect suppressed • suppressed for xF<0 for all mechanisms • good agreement with STAR data AN (p↑pπ0X)

  25. Intrinsic kT (continued) Boglione In the same model it was shown that • AN(p↑pDX)is an ideal process to study the Sivers distribution functions of quarks and gluons • TheHermes data can be described as well as the unpolarised Cahn asymmetries from EMC using Prokudin

  26. p↑ p↑ cross section in NLO Mukherjee • first NLO calculation • example: prompt photon at Phenix • scale dependence significantly reduced • study of K-factors for DY Ratcliffe

  27. Hermes Collins & Sivers Schnell

  28. COMPASS Collins & Sivers Pagano Collins Sivers

  29. Dihadron fragmentation h1 quark h2 Bacchetta • New quark polarimeter • simpler, no kT convolution, cf van der Nat Joosten

  30. More Asymmetries Gamberg • Boer-Mulders function • AUL • Model for transversity and intrinsic motion of quarks • Chiral-odd twist-3 DF e(x) • New observables from color gauge invariance Kinney Zavada Wakamatsu Pijlman

  31. Spin transfer to Λ • Spin transfer to Λ Alexakhin • transverse Λ polarisation Friedrich Belostotski

  32. Exclusive ρ production • SDME: • Model Neyret Goloskokov

  33. GPDs • DVCS Beam Charge Asymmetry new: deuteron • Hard exclusive ππ • Exclusive πand vector mesons • Hermes recoil detector Marukyan Fabbri Rostomyan Stewart

  34. More from theory Leader • Spin sum rule revisited • problem in derivation of • rigorous treatment yields miraculously same SR • new sum rule for transverse spin • Higher twist resummation • Asymmetries in SIDIS Teryaev Di Salvo

  35. Fragmentation functions • Determination of polarised fragmentation from Belle data in progress • Possible difficulties with LUND fragmentation at low energies • Q2 dependence of GDH Seidl Kotzinian Nagaitsev

  36. Personal Impression • Two new facilities are working perfectly: RHICand COMPASS • Enormous progress on theory of transverse spin and SSA • Is ΔG/G small? Exciting times ahead

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