1. Jlab, June 18, 2010 1 H. Avakian, N. Kalantarians CLAS & CLAS12 Measurements with Polarized Targets Workshop on High Luminosity Polarized Targets for the 12GeV Era JLab, June 18

2. Jlab, June 18, 2010 2 Outline Transverse structure of the nucleon and partonic correlations Physics motivation k T -effects with unpolarized and longitudinally polarized target data –Double spin asymmetries –Single Spin Asymmetries Physics with transversely polarized hadrons and quarks –k T -effects and SSA in pion production –correlations between transverse degrees of freedom Studies of 3D PDFs at CLAS at 6 GeV and beyond Summary

3. Jlab, June 18, 2010 3 Structure of the Nucleon GPDs/IPDs H,E,…H T d2kTd2kT d2kTd2kT TMD PDFs f 1 u (x,k T ),.. h 1 u (x,k T ) W p u (k,r T ) “Mother” Wigner distributions d2rTd2rT PDFs f 1 u (x),.. h 1 u (x) Analysis of SIDIS and DVMP are complementary d2rTd2rT

4. Jlab, June 18, 2010 4 k T -dependent PDFs and FFs: “new testament” No analog in twist-2 appear in sin  moment of A LU and A UL quark-gluon-quark correlations responsible for azimuthal moments in the cross section Baccetta, Diehl, Goeke, Metz, Mulders, Schlegel EPJ-2007

5. Jlab, June 18, 2010 555 SIDIS: partonic cross sections kTkT P T = p ┴ +z k T p┴p┴ Ji,Ma,Yuan Phys.Rev.D71:034005,2005 Is the info on x-k T correlations accessible in k T integrated observables?

6. Jlab, June 18, 2010 6 Collins Effect: azimuthal modulation of the fragmentation function D(z,P T )=D 1 (z,P T )+H 1 ┴(z,P T ) sin(  h  S’ ) spin of quark flips wrt y-axis  S’ =  -  S sin(  h  S ) CC SS STST y x hh PTPT sTsT  S’ CC F UT ∞h 1 H 1 ┴ s T (q×P T )↔ H 1 ┴ sin(2  h ) CC x PTPT hh S=hS=h y y x SS hh PTPT  S =  +  h x PTPT hh S=S= y hadronizing quark Intial quark polarization HT function related to force on the quark. M.Burkardt (2008)

7. Jlab, June 18, 2010 77 Sivers mechanisms for SSA - Correlation between quark transverse momentum and the proton spin SS x  kT PTPT Proton polarization SS SIDIS Drell-Yan M.Burkardt (2000) HT asymmetries (T-odd) No leading twist, provide access to quark-gluon correlations

8. Jlab, June 18, 2010 8 H. Avakian, JLab, April 26 88 Quark distributions at large k T : lattice Analysis of same distributions using gaussian distributions in terms of f 1 &g 1 and q+/q- yield different PDFs. B.Musch arXiv:0907.2381 8 H. Avakian, JLab, May 3

9. Jlab, June 18, 2010 999 Quark distributions at large k T : lattice Higher probability to find a d-quark at large k T B.Musch arXiv:0907.2381 H. Mkrtchyan et al.H. Mkrtchyan et al. Phys.Lett.B665:20-25,2008.

10. Jlab, June 18, 2010 10 CLAS slightly lower, but may have bigger Anselmino et al from EMC data → = 0.25 Wider at smaller beam energies? Transverse momentum distributions of hadrons Gauss 10 H. Avakian, JLab, May 3

11. Jlab, June 18, 2010 11 CLAS12 Solenoid 5T CTOF SVT Central Detector DC R1, R2, R3 LTCC FTOF PCAL EC HTCC TORUS Forward Detector Forward carriage Track resolution:  p (GeV/c) 0.003p + 0.001p 2  (mr) < 1  (mr)< 3 Wide detector and physics acceptance (current/target fragmentation) High beam polarization 85% High target polarization 85% Lumi > 10 35 cm -1 s -1

12. Jlab, June 18, 2010 12 Horizontal DNP Polarized Target. Field provided by warm bore solenoid. Center of the target is at 2 m from the solenoid entrance, surrounded by SVT. Beam along axis of refrigerator. 4 He Evaporation Refrigerator. One target cell (no ladder). UVa, ODU, CNU, JLab CLAS Longitudinally Polarized Solid Target Outer vacuum jacket 1 K heat exchanger separator  wave guide Beam tube LHe transfer line He-4 Pump Out Needle Valves He-4 Pumping tube Heat shield LHe fill tube 10 cm Beam

13. Jlab, June 18, 2010 13 CLAS12: Kinematical coverage Large Q 2 accessible with CLAS12 are important for separation of HT contributions Q 2 >1GeV 2 W 2 >4 GeV 2 (10) y<0.85 M X >2GeV SIDIS kinematics eXeX

14. Jlab, June 18, 2010 14 Complete azimuthal coverage crucial for separation of sin  sin2  moments Longitudinal Target SSA measurements at CLAS 0.12<x<0.48 Q 2 >1.1 GeV 2 P T <1 GeV W 2 >4 GeV 2 0.4<z<0.7 M X >1.4 GeV y<0.85 Large sin  for all pions and no indication of sin2  for  0 s suggests Sivers dominance (E05-113)

15. Jlab, June 18, 2010 15 A LL P T -dependence in SIDIS M.Anselmino et al hep-ph/0608048 New experiment with 10 times more data will study the P T -dependence for different quark helicities and flavors for bins in x to check if  0 <  2  0 2 =0.25GeV 2  D 2 =0.2GeV 2 0.4<z<0.7 E05-113

16. Jlab, June 18, 2010 16 Extracting widths from A 1 Assuming the widths of f 1 /g 1 x,z and flavor independent Anselmino et al Collins et al Fits to unpolarized data

17. Jlab, June 18, 2010 17 Pros 1.Small field (∫Bdl~0.005-0.05Tm) 2.Small dilution (fraction of events from polarized material) 3.Less radiation length 4.Less nuclear background (no nuclear attenuation) 5.Wider acceptance much better FOM, especially for deuteron Cons 1.HD target is highly complex and there is a need for redundancy due to the very long polarizing times (months). 2.Need to demonstrate that the target can remain polarized for long periods with an electron beam with currents of order of 1-2 nA 3.Additional shielding of Moller electrons necessary CLAS transversely polarized HD-Ice target Heat extraction is accomplished with thin aluminum wires running through the target (can operate at T~500-750mK) HD-Ice target at ~2nA ~ NH3 at 5 Na (L~5.10 33 cm -2 s -1 ) HD-Ice target vs std nuclear targets Multiple scattering and attenuation in nuclear environment introduces additional P T -dependence for hadrons  + yield ratios to deuteron

18. Jlab, June 18, 2010 18 Collins SSAs CLAS with a transversely polarized target will allow measurements of transverse spin distributions and constrain Collins fragmentation function Anselmino et al H.A.,A.Efremov,P.Schweitzer,F.Yuan helicity-transversity=pretzelosity CLAS E08-015 (2011)

19. Jlab, June 18, 2010 19 Measurement of Sivers function and GPD-E DVCS Transverse asymmetry (function of momentum transfer to proton) is large and has strong sensitivity to GPD - E CLAS will provide a measurements of Sivers asymmetry at large x, where the effect is large and models unconstrained by previous measurements. Meissner, Metz & Goeke (2007) GPD-E=0 (DVCS) (SIDIS) CLAS E08-015

20. Jlab, June 18, 2010 20 Summary Upcoming JLab SIDIS experiments at 6 and 12 GeV will significantly improve the statistical precision of polarized target data, allowing studies of correlations between longitudinal and transverse degrees of freedom Measurements of TMDs at JLab in the valence region provide important input into the global analysis of Transverse Momentum Distributions (involving HERMES,COMPASS,RHIC,BELLE,BABAR+JPARC,GSI,EIC) Measurements of azimuthal dependences of double and single spin asymmetries in SIDIS (TMDs) indicate that there are significant correlations between spin and transverse momentum distribution of quarks. Sizable higher twist asymmetries measured in SIDIS indicate the quark-gluon correlations may be significant at moderate Q 2.

21. Jlab, June 18, 2010 21 JLab, Nov 25 21 Support slides….

22. Jlab, June 18, 2010 22 SIDIS (  *p->  X) x-section at leading twist Measure Boer-Mulders distribution functions and probe the polarized fragmentation function Measurements from different experiments consistent TMD PDFs

23. Jlab, June 18, 2010 23 Nonperturbative TMDPerturbative region Boer-Mulders Asymmetry with CLAS12 & EIC CLAS12 and ELIC studies of transition from non-perturbative to perturbative regime will provide complementary info on spin-orbit correlations and test unified theory Transversely polarized quarks in the unpolarized nucleon - CLAS12 EIC ep 5-7 GeV50-150 GeV sin(  C ) =cos(2  h )

24. Jlab, June 18, 2010 24 Nonperturbative TMD Perturbative region P T -dependence of beam SSA  sin  LU(UL) ~F LU(UL) ~ 1/Q (Twist-3) 1/P T Check of the higher twist nature of observed SSA critical SSA test transition from non-perturbative to perturbative region 1/Q

25. Jlab, June 18, 2010 25 A 1 P T -dependence CLAS data suggests that width of g 1 is less than the width of f 1 Anselmino Collins

26. Jlab, June 18, 2010 26 Kotzinian-Mulders Asymmetries B.Musch arXiv:0907.2381 B.Pasquini et al, arXiv:0910.1677 HERMES CLAS (5 days) Worm gear TMDs are unique (no analog in GPDs)

27. Jlab, June 18, 2010 27 Collins fragmentation: Longitudinally polarized target  UL ~ KM curves,  QSM from Efremov et al Kotzinian-Mulders Asymmetry KM sin2  moment, sensitive to spin-orbit correlations: the only leading twist azimuthal moment for longitudinally polarized target More info will be available from SIDIS (COMPASS,EIC) and DY (RHIC,GSI) Transversely polarized quarks in the long. polarized nucleon

28. Jlab, June 18, 2010 28 cos  moment in A LL -P T -dependence P T -dependence of cos  moment of double spin asymmetry is most sensitive to k T - distributions of quarks with spin orientations along and opposite to the proton spin. hep-ph/0608048  0 2 =0.25GeV 2  D 2 =0.2GeV 2 CLAS PRELIMINARY

29. Jlab, June 18, 2010 29 CLAS configurations  e  ep→e’  X  Polarizations:  Beam: ~80%  NH3 proton 80%,ND3 ~30%  HD (H-75%,D-25%) 1)Polarized NH3/ND3 (no IC, ~5 days) 2)Polarized NH3/ND3 with IC 60 days 3)Polarized HD-Ice (no IC, 25 days) Inner Calorimeter Transversely polarized targetLongitudinaly polarized target

30. Jlab, June 18, 2010 30 CLAS Longitudinally polarized target run ( eg1-dvcs) Helium tube Polarized target Inner Calo

31. Jlab, June 18, 2010 31 eg1-dvcs Run Conditions Helium tube Polarized target Inner Calo 7.5mm Beam polarization: >80% Target polarization: >75% Rastering: R=~7.mm eg1-dvcs

32. Jlab, June 18, 2010 32 eg1-dvcs: Monitoring polarizations Monitoring the time dependence of the product of target and beam polarizations using the elastic asymmetry Monitoring the time dependence of the beam polarization using the single spin asymmetry in ep→e’  X HWP→IN HWP→OUT

33. Jlab, June 18, 2010 33 Scattering of 5.7 GeV electrons off polarized proton and deuteron targets SIDIS with JLab at 6 GeV  DIS kinematics, Q 2 >1 GeV 2, W 2 >4 GeV 2, y<0.85  0.4>z>0.7, M X 2 >2 GeV 2 2 eXeX Large P T range and full coverage in azimuthal angle  crucial for studies

34. Jlab, June 18, 2010 34 e1&eg1-dvcs: Monitoring and calibration IC operating in high background was stable. IC time and energy resolutions resolutions after calibration using 2 photon events.

35. Jlab, June 18, 2010 35 SSA with long. polarized target quark polarization

36. Jlab, June 18, 2010 36 SSA with long. polarized target quark polarization

37. Jlab, June 18, 2010 37 SSA with unpolarized target quark polarization

38. Jlab, June 18, 2010 38 SSA with unpolarized target quark polarization

39. Jlab, June 18, 2010 39 Beam SSA: A LU from CLAS @ JLab 0.5<z<0.8 Beam SSA from hadronization (Collins effect) by Schweitzer et al. Photon Sivers Effect Afanasev & Carlson, Metz & Schlegel Beam SSA from initial distribution (Boer-Mulders TMD) F.Yuan using h 1 ┴ from MIT bag model

40. Jlab, June 18, 2010 40 JLab, Nov 25 40

41. Jlab, June 18, 2010 41 JLab, Nov 25 41 CLAS vs CLAS12? Existing inconsistencies between HERMES and COMPASS require new independent input. CLAS data will be crucial in developing global analysis of 3D parton distributions, TMDs GPDs and Wigner distributions. Study the Q2 dependence of different SSA at fixed Bjorken-x will require measurements with different beam energies, including 6 GeV. Virtual photon has some angle with beam direction, so measurements with longitudinal and transverse target are important for each other. Enables early understanding of higher order corrections and higher twist contributions. CLAS data at 6 GeV will be important to analyze future CLAS12 data (different systematics). Reaction asymmetries from events ray traced back to vertex gives tomographic decomposition of target polarization vs e running time. -> essential to optimize plans for 12 GeV experiments

42. Jlab, June 18, 2010 42 JLab, Nov 25 42 Transverse force on the polarized quarks Interpreting HT (quark-gluon-quark correlations) as force on the quarks (Burkardt hep-ph:0810.3589) Quark polarized in the x-direction with k T in the y-direction Force on the active quark right after scattering (t=0)

43. Jlab, June 18, 2010 43 JLab, Nov 25 43 SSA with unpolarized target quark polarization

44. Jlab, June 18, 2010 44 JLab, Nov 25 44 SSA with unpolarized target quark polarization

45. Jlab, June 18, 2010 45 JLab, Nov 25 45 SSA with unpolarized target quark polarization

46. Jlab, June 18, 2010 46 JLab, Nov 25 46 SSA with unpolarized target quark polarization

47. Jlab, June 18, 2010 47 JLab, Nov 25 47 Beam SSA: A LU from CLAS @ JLab 0.5<z<0.8 Beam SSA from hadronization (Collins effect) by Schweitzer et al. Photon Sivers Effect Afanasev & Carlson, Metz & Schlegel Beam SSA from initial distribution (Boer-Mulders TMD) F.Yuan using h 1 ┴ from MIT bag model 5.7 GeV  + 4.3 GeV  + 5.7 GeV  0 Beam SSA for  0 and  + are comparable indicating small Collins type contributions

48. Jlab, June 18, 2010 48 JLab, Nov 25 48 Inbendin/outbending configurations Different polarities increase the acceptance of positive and negative hadrons.