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) x F 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) k T 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 A TT for Small Q T 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, p T = GeV/c   0 – E704, PLB261 (1991) 201.   +/- - E704, PLB264 (1991) 462. 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. A Brief History … 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 A N by removing leading twist or collinear restriction (by going twist-3 or k T 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. Kane, Pumplin, Repko ‘78

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

6 E(z 1,z 2 ) : quark-gluon correlation at final state G(x 1,x 2 ) : quark-gluon correlation at initial state (co-linear factorized) Twist-3 correlation functions and A N ^ qTqT d  /dq T  QCD q T <<Q q T ~Q  QCD << q T << Q TMD Twist3 How those two mechanisms connected ? Q Qui, Starman Koike

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

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

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

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 q T << Q  Twist3 = co-linear factorization twist-3  QCD << q T ~ Q  Those 2 agrees at  QCD << q T << 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” Bacchetta, Bomhof, Mulders, Pijlman Collins; Belitsky, Ji, Yuan; Boer, Mulders, Pijlman Ji, Qiu, Yuan, Vogelsang

11 New Insights from Recent Theoretical Works  Hadron tomography with impact parameter dependent PDF and connection to Sivers DF Burkardt  Gluon Saturation & A N Boer, Dumitru,Hayashigaki  Rich phenomenology to fit data & make predictions  By both TMD and Twist-3 framework  For A N 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 New Experimental Results  Hermes + Compass + Jlab (See Next Talks)  Collins FF STAR  A N ( x F,p T ) for inclusive  0  A N for Di-jet  A N for inclusive  +-  A N for inclusive K+-  A N for inclusive p+-  A N for inclusive  0  A N for J/psi  k T Asymmetry with Longitudinally Polarization  Great success of run6  L~1/pb/day  P~60%

13 π 0 A N at √s=200 GeV : x F -dependence A N at positive x F grows with increasing x F A N at negative x F is consistent with zero Run 6 data at =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 STAR Nogach

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

15 A N (p T ) in x F -bins Combined data from three runs at =3.3, 3.7 and 4.0 In each x F bin, does not significantly changes with p T Measured A N is not a smooth decreasing function of p T as predicted by theoretical models STAR Nogach

16 A N at 200 GeV 2.3 deg 4.0 deg 2.3 deg  +-  +-  +- Lee

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

18 A N at 62 GeV 2.3 deg  +-  +- Lee

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

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

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 jetCollins x Transversity p+p -> di-hadron (near side)Collins x Transversity (Interference FF) p+p -> jetSivers p+p -> photonSivers 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 Measured Sivers A N for Di-jets vs. Theory Model w/o hadronization, integrated over STAR , 5<p T <10 GeV/c, includes only quark Sivers -- predicts A N ~ A N HERMES where q Sivers dominates Sign of predictions reversed to adhere to Madison A N sign conventio STAR measured A N all consistent with zero  both quark and gluon Sivers effects much smaller in pp  di-jets than in HERMES SIDIS !! Emphasizes (80%+) gluon Sivers Emphasizes (50%+ ) quark Sivers STAR Balewski

23 k T Asymmetry in Longitudinally Polarized pp Like HekicityUnlike 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 PRELIMINAR Y A 0 (cos(2   )) momentsA 12 (cos(       )) moments R. Seidl ’ s Talk on Friday

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

26 Summary  New precise data of inclusive hadron A N from RHIC  Mapping A N in x F, p T 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 A N (x F,p T,sqrt(s))?  Can we understand A N of K-?  Can we understand proton/Anti-proton?  Can we understand Sivers DF from Hermes vs STAR?  Will we see A N 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 The Nucleon Spin Puzzle Longitudinal 1/2 = 1/2  +  G + L L ~0.6 from EJ-sum rule ~0.2 from DIS “spin crisis” RHIC Spin & SIDIS DVCS Spin Sum Rules Sivers DF Collins FF from Belle SI-DIS & RHIC Spin ~0.6 from Lattice QCD No gluon “Recovery” of EJ-sum rule? Transverse 1/2 = 1/2  L T Bakker, Leader, Trueman Phys.Rev.D70:114001,2004

Backup

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