1. + http://panda.unm.edu/fields/partonorbital.html G.Bunce (RBRC)
B. Hannafious (NMSU)
A.Miller (TRIUMF)
D.Hasch(DESY) +

6. The total intrinsic k┴ carried by quarks
Extraction of the Sivers function
What do we learn from it?
k┴ and orbital angular momentum
Orbiting quarks … ? ?
Mauro Anselmino, Parton Orbital Angular Momentum, RBRC-UNM Workshop, Albuquerque, 24-26/02/2006

7. predictions for JLab, proton target

8. Sivers functions extracted from AN data in
give also opposite results, with

9. k┴ and orbital angular momentum (case of 2 quarks)
Does
imply ?
It depends on space distribution …… to be continued ……

10. University of New Mexico/RBRC
Douglas Fields
University of New Mexico/RBRC
Sivers Effect
Recently, at the RBRC Single Spin Workshop, Denis Sivers gave a nice conceptual (no twist-anything) picture of how orbital angular momentum could cause a single transverse spin asymmetry.
“Quantum Fan” description (top view – spin down):
No Sivers Effect
without interaction
with absorber –
Higher twist effect

11. RBRC and BNL Nuclear Theory
Werner Vogelsang
RBRC and BNL Nuclear Theory
fragm.,
0.25 GeV2
GRV, GRSV, KKP

15. Parton picture: Longitudinal and transverse variables
H.Avakian
“long before”

16. Extraction of GPD H from ALU moment
cLU
epg
ALU/cLU ~
x(F1+F2)H +kF2E
~20%
2<Q2<2.4 GeV
Red[blue] points correspond to projected ALU [un]corrected for p0 (bin by bin)
H stands for the ratio of the ALU and prefactor calculated for all events in a bin (averaged over f)
Curves are for a simple model for CFF H (blue) and H+…(red)

17. Exclusive r0 production on transverse target
2D ┴(Im(AB*))/p
AUT = -
|A|2(1-x2) - |B|2(x2+t/4m2) - Re(AB*)2x2
A ~ 2Hu + Hd
B ~ 2Eu + Ed r0
A ~ Hu - Hd
B ~ Eu - Ed r+ r0
Eu, Ed needed for
angular momentum
sum rule.
(60 days)
K. Goeke, M.V. Polyakov,
M. Vanderhaeghen, 2001
Asymmetry is a more appropriate observable for GPD studies at JLab energies as possible corrections to the cross section are expected to cancel

18. Target SSA measurements at CLAS
ep→e’pX
W2>4 GeV2
p1sinf+p2sin2f
CLAS PRELIMINARY
Q2>1.1 GeV2
y<0.85
0.4<z<0.7
MX>1.4 GeV
PT<1 GeV
0.12<x<0.48
p1= 0.059±0.010
p2=-0.041±0.010
p1=-0.042±0.015
p2=-0.052±0.016
p1=0.082±0.018
p2=0.012±0.019
Significant SSA measured for pions with longitudinally polarized target
Complete azimuthal coverage crucial for separation of sinf, sin2f moments

24. COMPASS plans to measure GPDs
Jean-Marc Le Goff
DAPNIA/CEA-Saclay
24 Feb 2006, Albuquerque
workshop on Orbital Angular Momentum
The COMPASS experiment
GPDs at COMPASS
now: deep r production
≥2010: DVCS and HEMP

25. Conclusions on rho SCHC → R stot + R → sL
when Q2 > 2 → R > 1 : accurate sL
we have transv. target spin asym → E/H
important for Ji sum rule (∫E+H)
exploratory measurement
(no exclusivity, nuclear target)

26. Additions to COMPASS setupμ’ p’ μ
2.5m liquid H2 target
to be designed and built
L = cm-2 s-1
 ECal 1 or 2
  12°
Exclusivity: at high energy
dDM2 = d[(mp+mπ)2-mp2] > 1 GeV2
need 0.25 GeV2 for DM cut
 hermetic detector
Recoil detector
to insure exclusivity
to be designed and built
+ additional calorimeter
at larger angle

27. at 100 GeV assuming: L = 1.3 1032 cm-2 s-1 φ φ φ
BCA
Q2=40.5 GeV2
x = 0.05 ± 0.02
Model 1: H(x,0,t) ~ q(x) F(t)
Model 2:
H(x,0,t) = q(x) e t <b2>
= q(x) / xα’t
assuming:
L = cm-2 s-1
150 days
efficiency=25%
2 bins shown out of 18:
3 bins in xBj= 0.05, 0.1, 0.2
6 bins in Q2 from 2 to 7 GeV2 φ φ
BCA
x = 0.10 ± 0.03 φ

31. RIKEN/BNL Research Center Brookhaven National Laboratory
Feng Yuan
RIKEN/BNL Research Center
Brookhaven National Laboratory
Outline
Why naïve parton model fails for SSAs
Two mechanisms: Sivers and twist-3
Unifying these two
What we learn from SSA?
Summary

32. TMD Factorization When q?¿ Q, a TMD factorization holds
When q?ÀQCD, all distributions and soft factor can be calculated from pQCD, by radiating a hard gluon
In the intermediate range QÀq?ÀQCD 2 approaches overlap and should give the same answer !!!

33. Final Results P? dependence Which is valid for all P? range
Sivers function at low P?
Qiu-Sterman Twist-three

34. Using Dijets to Measure the Gluon Sivers Functions at STAR
Renee Fatemi
Massachusetts Institute of Technology
February 28, 2005

35. Sivers Effect in Dijets
Jet #2  SP AN 
Deviations from  =  due to Partonic kT
Gluon = (U + D) / 2
Gluon = 0
Gluon = D
Gluon = D + √kT2 = 2.5
Maximal Effects at  = This region experimentally available!
W.Vogelsang and D.Boer Phys Rev D 69 (2004)

36. Summary and Discussion
STAR Collaboration is invested in studying all aspects of spin puzzle.
Transverse running has high priority for STAR in 2006.
Recent developments in hardware, shielding and triggering should enable us to produce first statistically significant measurement of dijet  asymmetry.
Do we need to worry about Collins effects from first gluon scattered from polarized quark? How does this effect vary with cone size?
If size of partonic kT is independent of hard scattering scale (jet pT) then shouldn’t this asymmetry become smaller at higher jet pT?
How will Sivers Functions be extracted from this asymmetry? What is the status of the necessary factorization theorems?
Can we extract Lg from Sivers?

37. Forward Particle Production and Transverse Single Spin Asymmetries
OUTLINE
Transverse single spin effects in p+p collisions at s=200 GeV
Towards understanding forward p0 cross sections
Plans for the future
L.C. Bland
Brookhaven National Laboratory
RBRC Workshop on Parton Orbital Angular Momentum
Albuquerque February 2006

38. AN(pT) from run3+run5 at √s=200 GeV
Uses online beam polarization values
Combined statistics from run3 and run5 with xF>0.4
There is evidence that analyzing power at xF>0.4 decreases with increasing pT
To do: systematics study

39. Plans for the Future
STAR Forward Pion Detector upgrade (FPD++) planned as an engineering test of the FMS during RHIC run 6
STAR Forward Meson Spectrometer (FMS) planned for installation by RHIC run 7
Disentangle the dynamical origins to transverse SSA in p+p collisions via measurements of AN for
jet-like events
direct photon production

40. Sample decays on FPD++ H.A. Separate photons from p0?
With FPD++ module size and electronic dynamic range, have >95% probability of detecting second photon from p0 decay.

41. Outline Introduction Drell-Yan experiment SSA measurements Summary
Yuji Goto (RIKEN/RBRC)
SSA Measurements with Primary Beam at J-PARC
Outline
Introduction
J-PARC
spin physics with primary beam at J-PARC
Drell-Yan experiment
SSA measurements
Summary

42. SSA on Drell-Yan no final-state effect
sensitive to Sivers effect at low qT: qT << Q
H.A. In the region of 0.2<x<0.4 should be able to measure also the Mulders function measured at CLAS
integrated over qT
Sivers function fit from Vogelsang & Yuan: PRD 72, (2005).
(from Xiangdong Ji’s slide at J-PARC hadron
structure workshop at KEK, December, 2005)

43. Summary
For the spin physics program with primary beam at J-PARC, study group for the polarized proton acceleration and the physics experiment were formed, and discussions are underway
Measurement of the orbital angular momentum component in the nucleon is one of the most important goal of the spin physics program at J-PARC
Drell-Yan experiments are planned
SSA measurements of Drell-Yan, pions, D-mesons, etc.
gluon polarization at large-x, transversity, etc.
Physics and detector studies are ongoing
Collaboration with many groups in the world is very important
D-mesons from intrinsic charm  no QCD applicable (S.B.)