Transverse spin phenomena in pp and polarized fragmentation

1. Transverse spin phenomena in pp and polarized fragmentation Akio Ogawa, BNL 2006 Oct 3

2. Related Experimental Talks (7 talks) Tuesday • J.H. Lee (BNL) xF Dependent Single Spin Asymmetries for +-, K+-, p and pbar in Polarized p+p Collisions at sqrt(s)=200 GeV and 62 GeV (Brahms) • Mickey Chiu (Illinois) Single Spin Transverse Asymmetries of Neutral Pions at Forward Rapidities in sqrt(s)=62 GeV Polarized Proton Collisions at RHIC (Phenix) • Larisa Nogach (Inst. of High Energy Phys.) Measurement of Transverse Spin Effects with the Forward Pion Detector of STAR • Han Liu (New Mexico State) Transverse Single Spin Asymmetry Measurement with Heavy Flavors in Polarized p+p Collisions at RHIC (Phenix) • Jan Balewski (Indiana) Measurement of Sivers Asymmetry for Di-jets in 200 GeV pp Collisions at STAR Friday • Douglas Fields (Univ. of New Mexico) kT Asymmetry in Longitudinal polarized Collisions (Phenix) • Ralf Seidl (Illinois) Chiral-Odd Fragmentation Function Measurements at Belle Other Plenary Talks : • Anna Martin (Trieste) Transverse Spin Phenomena in Lepton Scattering • Harut Avakian (JLAB) Generalized Parton Distributions • Alessandro Bravar (Geneva) Spin Physics in Forward Scattering

3. Related Theoretical Talks (18 Talks) Tuesday • Matthias Burkardt(New Mexico State) Hadron Tomography • Werner Vogelsang (BNL) Single-Spin Asymmetries • Alessandro Bacchetta (DESY) Transverse-Momentum Dependent Functions in Semi-Inclusive DIS • Leonard Gamberg (Penn. State) Transverse Quark Spin Effects in Azimuthal Asymmetries in SIDIS and DY • Feng Yuan (RBRC) Unique Description of Single Transverse-Spin Asymmetries in DIS and Hadron Collisions • Kazuhiro Tanaka (Juntendo) A New Approach For Single Transverse-Spin Asymmetries From Twist-3 Soft-Gluon Mechanism • Yuji Koike (Niigata) Single Transverse Spin Asymmetry for Semi-Inclusive Deep Inelastic Scattering • Umberto D'Alesio (Cagliari) Transverse Momentum Dependent Distributions in Hadronic Collisions • Cedran J. Bomhof (Amsterdam) Sivers Effect Asymmetries in Hadron-Hadron Collisions • Umberto D'Alesio (Cagliari) Constraints on Gluon Sivers Distributions from RHIC Results Thursday • Anatoly V. Efremov (JINR) Collins Effect in SIDIS and in Electron-Positron-Annihilation • Alexei Prokudin (Torino) Collins Effect in polarized SIDIS and e+e- Data • Genis Musulmanbekov (JINR) Single Spin Asymmetry in Strongly Correlated Quark Model • Hiroshi Yokoya (Niigata) Threshold Resummeation Effects in the Polarized DY mechanism • Hiroyuki Kawamura (RIKEN) QCD Prediction of ATT for Small QT Dimuon Production in pp and ppbar Collisions Friday • Daniel Boer (Amsterdam) Gluon Saturation Effects On Single Spin Asymmetries • Marco Radici (Pavia) Transversity and Inclusive Two-Pion Production • Alessandro Drago (Ferrara) Measuring the Sea Polarization by Drell-Yan Production at Moderate Energies • More talks on GPDs, etc….

4. s=20 GeV, pT=0.5-2.0 GeV/c • 0 – E704, PLB261 (1991) 201. • +/- - E704, PLB264 (1991) 462. A Brief History… • At leading twist and with collinear factorization, the chiral properties of QCD predict small analyzing powers for particle production with transversely polarized protons colliding at high energies. Kane, Pumplin, Repko ‘78 • The FermiLab E-704 experiment found strikingly large transverse single-spin effects in p+p fixed-target collisions with 200 GeV polarized proton beam. • Around same time, pQCD was examined and effects were found which may explain large AN by removing leading twist or collinear restriction (by going twist-3 or kT factorization). • Recently, large transverse single-spin effects were observed in semi-inclusive electro-production experiments (DESY,CERN,JLab) as well as p+p collisions (AGS, RHIC), which also triggered advancements in theoretical understandings.

5. SP SP kT,q p p p p Sq kT,π unpol kT,q Sq p Boer-Mulders mechanism: Correlation between parton kT and parton spin * Transversity kT,q Sp p Sq Transverse Momentum Dependent PDFs and AN Sivers mechanism:Correlation between nucleon spin and parton kT Collins mechanism:Transversity (quark polarization) * asymmetry in the jet fragmentation Phys Rev D41 (1990) 83; 43 (1991) 261 Nucl Phys B396 (1993) 161 Sq Boer, Mulders

6. How those two mechanisms connected ? d/dqT qT~Q Twist3 qT<<Q TMD qT QCD QCD << qT << Q Q (co-linear factorized) Twist-3 correlation functions and AN ^ G(x1,x2) : quark-gluon correlation at initial state E(z1,z2) : quark-gluon correlation at final state Qui, Starman Koike

7. ~0.6 from EJ-sum rule ~0.2 from DIS “spin crisis” RHIC Spin & SIDIS DVCS Transverse 1/2 = 1/2  + LT Bakker, Leader, Trueman Phys.Rev.D70:114001,2004 ~0.6 from Lattice QCD No gluon “Recovery” of EJ-sum rule? Sivers DF Collins FF from Belle SI-DIS & RHIC Spin The Nucleon Spin Puzzle Spin Sum Rules Longitudinal 1/2 = 1/2 + G + LL

8. BRAHMS Preliminary STAR Cross section at forward rapidity, NLO pQCD and AN PRL 92, 171801 (2004) nucl-ex/0602011 √s=200 GeV, <η> = 3.8 Asymmetry revealed at lower energies persists at √s=200 GeV Cross-section is consistent with NLO pQCD calculations

9. While at fixed target energy, it was not case…. Bourrely and Soffer (hep-ph/0311110, Data references therein) s=20 GeV, pT=0.5-2.0 GeV/c √s=23.3GeV • 0 – E704, PLB261 (1991) 201. • +/- - E704, PLB264 (1991) 462. Cross-section is NOT consistent with NLO pQCD calculations

10. New Insights from Recent Theoretical Works • Transverse spin sum rule (BLT sum rule) in spin2004 Phys.Rev.D70:114001,2004 • Relation between TMD PDF and Twist-3 Correlation Function • TMD = kT factorization twist-2 qT << Q • Twist3 = co-linear factorization twist-3 QCD << qT ~ Q • Those 2 agrees at QCD << qT << Q • Connection at moment: • Sivers DF “Modified” Universality, “Un-modified” • “Gauge link” factor • 1 for SIDIS • -1 for DY • 1/2 for q-q, factors for others sub-processes were calculated • Corresponding parts can be found in Twist-3 within “hard part” Ji, Qiu, Yuan, Vogelsang Collins; Belitsky, Ji, Yuan; Boer, Mulders, Pijlman Bacchetta, Bomhof, Mulders, Pijlman

11. New Insights from Recent Theoretical Works • Hadron tomography with impact parameter dependent PDF and connection to Sivers DF Burkardt • Gluon Saturation & AN Boer, Dumitru,Hayashigaki • Rich phenomenology to fit data & make predictions • By both TMD and Twist-3 framework • For AN of , k, p, jet, photon, J/psi, D, DY… • For xF, pT, sqrt(s) dependences • For SIDIS data • For e+e- data Yuan, Vogelssang, D'Alesio, Anselmino, Qui, Starman, Koike, Goek, Efremov, Prokudin, Melis, Murgia, Kouvaris… • Theorists are not Oracles and of course couldn’t know new results shown at this conference before they made the talk….. And we have new & exciting experimental results shown at this conference!!!

12. STAR New Experimental Results • Hermes + Compass + Jlab (See Next Talks) • AN for inclusive +- • AN for inclusive K+- • AN for inclusive p+- • Great success of run6 • L~1/pb/day • P~60% • AN(xF,pT) for inclusive 0 • AN for Di-jet • AN for inclusive 0 • AN for J/psi • kT Asymmetry with Longitudinally Polarization • Collins FF

13. STAR π0AN at √s=200 GeV : xF-dependence • AN at positive xF grows with • increasing xF • AN at negative xF is consistent • with zero • Run 6 data at <η>=3.7 are • consistent with the existing • measurements • Small errors of the data points • allow quantitative comparison • with theory predictions • Theory expects the reverse • dependence on η Nogach

14. STAR AN(pT) at xF > 0.4 Run3+Run5 data (hep-ex/0512013): • Online calibration of CNI • polarimeter • Hint of AN decrease with • increasing pT at pT~1-2 GeV/c • Run6 data: • more precise measurements • consistent with the previous runs in the overlapping pT region • complicated dependence on pT residual xF-dependence? => AN mapping in (xF,pT) plane is required Nogach

15. STAR AN(pT) in xF-bins • Combined data from three runs • at <η>=3.3, 3.7 and 4.0 • In each xF bin, <xF> does not • significantly changes with pT • Measured AN is not a smooth • decreasing function of pT • as predicted by theoretical • models Nogach

16. AN at 200 GeV +- +- 4.0 deg 2.3 deg +- +- 2.3 deg 2.3 deg Lee

17. Twist-3 calculation provide by F. Yuan +- +- 4.0 deg 2.3 deg +- +- 2.3 deg 2.3 deg Lee

18. AN at 62 GeV 2.3 deg +- +- 2.3 deg 2.3 deg +- Lee

19. Twist-3 calculation provide by F. Yuan 2.3 deg +- +- 2.3 deg • Beautiful data • |AN(-)| is bigger than AN(+) ? • AN(-) is as large as AN(+) ? • Anti proton? 2.3 deg +- Lee

20. AN for J/psi Disfavor the maximum contribution of gluon Sivers function AN of Mid-rapidity Neutral Pions and Charged Hadrons are very well constraint to ~0. Liu Phys. Rev. Lett. 95(2005)202001 PHENIX AN for 0 from Muon Piston Calorimeter is coming very soon!

21. Going Beyond Inclusive Measurements • Inclusive DIS Not sensitive • Semi-Inclusive DIS Collins, Sivers and more • Inclusive hadron production in pp Collins and Sivers are mixed • “Semi-Inclusive” pp • p+p -> jet -> hadron + rest of jet Collins x Transversity • p+p -> di-hadron (near side) Collins x Transversity • (Interference FF) • p+p -> jet Sivers • p+p -> photon Sivers • p+p -> di-jet, di-hadron (far side) Sivers • p+p -> l+l (DY) Sivers “Asymmetric jet correlations” in ppjet jet X Boer & Vogelsang (PRD 69) Cedran, Yuan

22. Emphasizes (80%+) gluon Sivers • Model w/o hadronization, integrated over STAR , 5<pT<10 GeV/c, includes only quark Sivers -- predicts AN ~ ANHERMES where q Sivers dominates • Sign of predictions reversed to adhere to Madison AN sign conventio • STAR measured AN all consistent with zero  both quark and gluon Sivers effects much smaller in pp  di-jets than in HERMES SIDIS !! STAR Measured Sivers AN for Di-jets vs. Theory Emphasizes (50%+ ) quark Sivers Balewski

23. kT Asymmetry in Longitudinally Polarized pp Like Hekicity Unlike Hekicity Large impact parameter Head on Orbital angular momentum may cause double spin asymmetry in width of di-jet after averaged over impact parameter D. Fields’s Talk on Friday

24. Collins asymmetries • 547 fb-1 charm corrected data sample, • UL and UC double ratios x A0 (cos(20)) moments A12 (cos(1 +2)) moments PRELIMINARY PRELIMINARY R. Seidl’s Talk on Friday

25. STAR Forward Meson Spectrometer (FMS) • FMS will provide full azimuthal coverage for range 2.5    4.0 • Broad acceptance in xF-pT plane for inclusive 0 , etc…production in p+p and d(p)+Au • Broad acceptance for -0 and 0-0 from forward jet pairs to probe low-x gluon density in p+p and d(p)+Au collisions MPC will provide full azimuthal coverage for range 3.1    3.7 and 2 < E(0) < 25GeV Raw AN() of 0 from run6 MPC North side is being installed now Muon Piston Calorimeter (MPC) Chiu

26. Summary • New precise data of inclusive hadron AN from RHIC • Mapping AN in xF, pT and sqrt(s) • Various channels : 0, +-, K +-, p +-, J/psi • Going beyond inclusive hadron measurements • Sivers DF measurement with di-jet production • New measurement of polarized FF • Large Collins FF observed by Belle • Great advancements in theoretical understandings • Relation between TMD and Twist-3 DF is now clearer • Sivers DF “universality” • Frameworks to fit & predict asymmetries for SIDIS & pp & ee

27. Questions for next 2 years • Can we understand AN(xF,pT,sqrt(s))? • Can we understand AN of K-? • Can we understand proton/Anti-proton? • Can we understand Sivers DF from Hermes vs STAR? • Will we see AN from “jet” & photon production? • Will we see Transversity * Collins FF (and BM * Collins FF) in jet production? • Will we see interference FF from Belle? • Is Collins FF really universal? • Formal factorization? • Can we get to orbital angular momentum contribution to nucleon spin from those measurements? • Can Global fit & Extraction of DFs/FFs from DIS, pp and ee done? • GSI? J-PARC? LHC? Burkardt; Brodsky, Hwang, Schmidt; Ji, Ma; Sivers

28. ~0.6 from EJ-sum rule ~0.2 from DIS “spin crisis” RHIC Spin & SIDIS DVCS Transverse 1/2 = 1/2  + LT Bakker, Leader, Trueman Phys.Rev.D70:114001,2004 ~0.6 from Lattice QCD No gluon “Recovery” of EJ-sum rule? Sivers DF Collins FF from Belle SI-DIS & RHIC Spin The Nucleon Spin Puzzle Spin Sum Rules Longitudinal 1/2 = 1/2 + G + LL

29. Backup

30. unpol kT,q Sq p kT,h Boer-Mulders mechanism: Correlation between parton kT and parton spin * Collins FF kT,q p Sq kT,h