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SUMMARY OF THE SPIN SESSION EXPERIMENT PART

SUMMARY OF THE SPIN SESSION EXPERIMENT PART. Hall B. Hall A. Two high-resolution 4 GeV spectrometers. Large acceptance spect. electron/photon beams. Beam: 160 GeV m ; 75% polarization Target: 6 LiD; 50% polarization. Hall C. Beam: 27.5 GeV e ± ; <50>% polarization

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SUMMARY OF THE SPIN SESSION EXPERIMENT PART

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  1. SUMMARY OF THE SPIN SESSIONEXPERIMENT PART

  2. Hall B Hall A Two high-resolution 4 GeV spectrometers Large acceptance spect. electron/photon beams Beam: 160 GeV m; 75% polarization Target: 6LiD; 50% polarization Hall C Beam: 27.5 GeV e±; <50>% polarization Target: (un)-polarized gas targets; <85%> polarization Beam: ≤6 GeV e-; 85% polarization Target: polarized targets 3He, 6LiD, NH3 Beams: 250 GeV pp; <60>% polarization Lumi: 1.2 1031cm-2s-1 7 GeV spectrometer, 1.8 GeV spectrometer, large installation experiments STAR Who is who?

  3. Naïve parton model Unpolarised structure fct. Gluons are important ! BUT Full description of Jq and Jg needs orbital angular momentum 1989 EMC measured S = 0.120 0.094 0.138 ± ± Spin Puzzle Sea quarksDqs DG What we are after?

  4. COMPASS:Valence PDFs • For LO: • Assuming: • Gv is 2.5sstat away from flavour • symmetric sea scenario

  5. Need longitudinal polarized deuterium target strange quark sea in proton and neutron identical fragmentation simplifies All needed information can be extracted from HERMES data alone inclusive A1,d(x,Q2)and kaon AK1,d (x,Q2) double spin asym. Kaon multiplicities  DQK and DSK Only assumptions used: isospin symmetry between proton and neutron charge-conjugation invariance in fragmentation dotted: CTEQ-6L & fit HERMES Preliminary dashed: dashed-dotted: HERMES: polarized and unpolarized s-PDF Fit x-dependence of multiplicities to get S(x) PDF and Kaon FF solid: S(x)= Q(x): CTEQ-6L & DSS s(x) + sbar(x)

  6. HERMES: polarized and unpolarized s-PDF Inclusive Asymmetry Kaon Asymmetry

  7. GLOBAL FITdeFlorian, Sassot, Stratmann, Vogelsang

  8. Measuring DG

  9. ALL from STARS jets

  10. ALL from p0,p±, at phenix

  11. COMPASS OPEN CHARM

  12. COMPASS HIGH-pT

  13. The 3rd Twist-2 structure function three quark distribution functions (DF) are necessary to describe the structure of the nucleon at LO q(x) f1q (x) unpolarised DF quark with momentum xP in a nucleon well known – unpolarised DIS • vector charge Dq(x) g1q(x) helicity DF quark with spin parallel to the nucleon spinin a longitudinally polarised nucleon known – polarised DIS  axial charge DTq(x) = q↑↑(x) - q↑↓(x) h1q(x), transversity DF quark with spin parallel to the nucleon spinin a transversely polarised nucleon  tensor charge largely unknown ALL 3 OF EQUAL IMPORTANCE

  14. Transversity DF q=uv, dv, qsea quark with spin parallel to the nucleon spinin a transversely polarised nucleon DTq(x) = q↑↑(x) - q↑↓(x) h1q(x), dq(x), dTq(x) • Properties: • probes the relativistic nature of quark dynamics • no contribution from the gluons  simple Q2 evolution • Positivity: Soffer bound…………….. • first moments: tensor charge………. • sum rule for transverse spinin Parton Model framework………… • it is related to GPD’s • is chiral-odd: decouples from inclusive DIS Soffer, PRL 74 (1995) Bakker, Leader, Trueman, PRD 70 (04)

  15. Collins Final on Deteron - COMPASS Federica Sozzi

  16. Collins FF from Belle

  17. Global Fit

  18. Global Fit For Collins FF and Transversity  Andreas Metz

  19. Final 2-hadron from Hermes Xiaorui Lu Also Measurements from COMPASS on Deuteron… F. Sozzi

  20. SIVERS Mechanism • The Sivers DF is probably the most famous between TMDs… • gives a measure of the correlation between the transverse momentum and the transverse spin • Requires final/initial state interactions of the struck quark with the spectator system and the interference between different helicityFock states to survive time-reversal invariance • Time-reversal invariance implies: • …to be checked • In SIDIS:

  21. Sivers Final on Deuteron from COMPASS

  22. Global Analysis Stefano Melis For Sivers DF  Andreas Metz

  23. Global Analysis II Stefano Melis

  24. AN(p) at √s = 62 GeV Submitted to Physical Review LettersarXiv:0801.1078 Twist 3 sivers • Large AN(p): 0.3-0.4 at xF~0.6 pT~1.3 GeV • Strong xF -pTdependence. Though|AN(p+)| ~ !AN(p-)| |AN(p+)/AN(p-)| decreases with xF-pT DIS, London, April 7-11, 2008

  25. Unifying 62 and 200 GeVBRAHMS + E704 E704 data – all pt (small star) pt>0.7 red star. DIS, London, April 7-11, 2008

  26. exclusive: all products of the reaction are detected missing energy (DE) and missing Mass (Mx) = 0 from DIS: ~0.3 The Hunt for Lq Study of hard exclusive processes leads toa new class of PDFs Generalized Parton Distributions possible access to orbital angular momentum

  27. unpolarized polarized quantum numbers of final state select different GPD vector mesons pseudo-scaler mesons DVCS AUT,sr,F,w AUT,sp+ AC,ALU,AUT, AUL GPDs Introduction What does GPDs charaterize? conserve nucleon helicity flip nucleon helicity not accessible in DIS

  28. ~ DsC~cosf∙Re{ H+ xH +… } ~ DsLU~sinf∙Im{H+ xH+ kE} DsUT polarization observables: ~ DsUL ~sinf∙Im{H+ xH+ …} beam target DVCS ASYMMETRIES  different charges: e+ e-(only @HERA!): H H ~ H DsUT ~sinf∙Im{k(H- E) + … } H, E kinematically suppressed x = xB/(2-xB ),k = t/4M2

  29. CLAS: BSA: coverage and f distributions Data integrated over t • 13 Q2, xB bins • 5 t bins • 12 f bins Fit =  sin/(1+cos Ph.D. Thesis of F.X. Girod

  30. CLAS e1-dvcs Hall A CLAS @ 4.3 GeV2 VGG(*) twist-2 (DD) VGG(*) twist-2 and 3 Regge model (**) CLAS: BSA: a vs. t (*) Guidal, Polyakov, Radyushkin, Vanderhaegen, PRD 72 (2005) (**) Cano and Laget, PL B551 (2003) GPD model overestimates the data arXiv: 0711.4805 [hep-ex] Submitted to PRL Ph.D. Thesis of F.X. Girod

  31. Sensitivity to Jq Hermes: Transverse Target Spin Asymmetry

  32. Hermes: Charge and Beam Spin Asymmetry Beam Charge Asymmetry

  33. Hermes: Charge and Beam Spin Asymmetry Beam Spin Asymmetry DVCS Ampl. Interference Ampl.

  34. Hermes: Charge and Beam Spin Asymmetry Heavy Targets Beam Charge Asymmetry Beam Spin Asymmetry • Why nuclear DVCS: • constrain nuclear GPDs • constrain models attempting • to describe nuclear matter • neutron and proton matter • distribution in nuclei

  35. What next? • More data • Hermes/Compass/RHIC/Jlab • New Data • Compass/RHIC… • New Experiments • Jlab@12/CompassII

  36. Thanks to all the participants of the Spin Session [apologies to all speakers not covered in this summary]

  37. … and pions

  38. COMPASS 2-hadrons, leading z-hadrons

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