Vincent Sulkosky
Massachusetts Institute of Technology
2011 JLab Users Group Meeting
June 8th, 2011
Transverse Momentum Dependent (TMD)
Parton Distributions
 TMD PDFs link
in DIS
Nucleon -> Pancake
 Intrinsic motion of partons
 Parton spin
 Spin of the nucleon
L ≠? 0
→Transverse motion
 Multi-Dimension structure
 Probes orbital motion of quarks
 A new phase of study, fast developing field
 Great advancement in theories (factorization, models, Lattice ...)
 Not systematically studied until recent years


Semi-Inclusive DIS (SIDIS): HERMES, COMPASS, Jlab-6GeV, ...
p-p(p_bar) process : FNAL, BNL, ...
Additional details in X. Qian’s and
A. Metz’s talks on June 7th.
Leading-Twist TMD PDFs
Quark polarization
Unpolarized
(U)
Nucleon Polarization
U
Longitudinally
Polarized (L)
Transversely
Polarized (T)
h1  =
f1 =
Boer-Mulders
h1L =
g1 =
L
Helicity
Worm Gear
(Kotzinian-Mulders)
h1 =
T
f 1T =
Transversity
g1T =
Sivers
Nucleon Spin
Quark Spin
Worm Gear
h1T =
Pretzelosity
: Survive trans. Momentum integration
Leading-Twist TMD PDFs
Quark polarization
Unpolarized
(U)
Nucleon Polarization
U
Longitudinally
Polarized (L)
Transversely
Polarized (T)
h1  =
f1 =
Boer-Mulders
h1L =
g1 =
L
Worm Gear
(Kotzinian-Mulders)
Helicity
h1 =
T
f 1T =
Transversity
g1T =
Sivers
Nucleon Spin
Quark Spin
Worm Gear
h1T =
: Probed by E06-010
Pretzelosity
Transversity

Characteristics of transversity





h1T = g1L for non-relativistic quarks
No gluon transversity in nucleon
Chiral-odd → difficult to access in inclusive DIS
Soffer’s bound |h1T| <= (f1+g1L)/2
q
Tensor Charge:



Integration of transversity over x.
An important quantity of nucleon.
Calculable in LQCD
q
Helicity
state
N
N
Sivers Function
• Left-right asymmetric quark distribution in a transversely polarized
nucleon
• Related to the angular momentum of quarks Lq
• Final state interactions (FSI) can lead to non-zero asymmetries
(Brodsky, Hwang, Schmidt, 2002)
• Imaginary part of interference
Lq=0 ✖ Lq=1 quark wave functions.
• Gauge invariance of QCD requires Sivers
function to flip sign between semi-inclusive
DIS and Drell-Yan:
f1Tq
SIDIS
  f1Tq
D Y
“Worm-Gear” Functions g1T

g1T =
 Leading twist TMD PDFs
 T-even, Chiral-even
 Dominated by real part of interference
between
L=0 (S) and L=1 (P) states
 Imaginary part -> Sivers effect
 No GPD correspondence
 a genuine sign of intrinsic transverse motion
Worm Gear
g1T (1)
S-P int.
TOT
P-D int.
 First TMDs in Pioneer Lattice
calculation

arXiv:0908.1283 [hep-lat], arXiv:1011.1213 [hep-lat]
Light-Cone CQM by B. Pasquini
B.P., Cazzaniga, Boffi, PRD78, 2008
Access TMDs through SIDIS
• Detect one hadron from fragmentation of the struck quark in
coincidence with the scattered electron
• Flavor tagging possible through fragmentation function
• z = Eh/ν at least > 0.2
Access TMDs through SIDIS
d
2
y2


2
2
dxdydS dzdh dPh  xyQ 2(1   )
{FUU ,T  ...
Boer-Mulder
cos( 2h )
UU
  cos(2h )  F
 ...
Unpolarized
 S L [ sin( 2h )  FULsin( 2h )  ...]
Transversity
/Collins
Sivers
Pretzelosity
 ST [ sin(h  S )  FUTsin(h S )
 sin(h  S )  ( FULsin(h S )  ...)
Polarized
Target
  sin(3h  S )  FUTsin( 3h S )  ...]
 S L e [ 1   2  FLL  ...]
Worm Gear
Polarized
Beam and
cos(h  S )
2
 ST e [ 1   cos(h  S )  FLT
 ...]} Target
SL, ST: Target Polarization; e: Beam Polarization
Separation of TMDs
Separate different effects through angular dependence
• Collins asymmetry:
Collins
AUT
 sin h  s  UT  h1  H1
• Sivers asymmetry:
Sivers
AUT
 sin h  s  UT  f1T  D1
• “Pretzelosity”:
Pretzelosity
AUT
 sin 3h  s  UT  h1T  H1
• Double-spin asymmetry:
cosh  s 
ALT
 cosh  s 
LT
 g1T  D1
E06-010 Experiment Setup
 Success full data taking 2008-09
 Polarized electron beam
Luminosity
Monitor
 ~80% polarization
 Fast Flipping at 30Hz
 Charge asymmetry:
controlled by online feed back at PPM level
 Polarized 3He target
 BigBite at 30º as electron arm
 Dipole magnet, Pe = 0.7 ~ 2.2 GeV/c
 MWDC/shower-preshow/scintillator
 HRSL at 16º as hadron arm
 QQDQ config, Ph = 2.35 GeV/c
 Scintillator/drift chamber/Cherenkov/RICH/ lead glass
Beam Polarimetry
(Møller + Compton)
Kinematic Coverage
x bin 1
<Q2> ~ 2.0 GeV2
<W> ~ 2.8 GeV
<z> ~ 0.5
2
3
4
Q2>1GeV2
W>2.3GeV
z=0.4~0.6
W’>1.6GeV
Angular Coverage
color coded for each target spin direction: up, down, left and right.
Collins:
Sivers and Worm-Gear:
Target spin orientations: up-down and left-right
(increases angular coverage)
HRS and BigBite Spectrometers
Particle Identification
Hadron Identification from HRS
Electron Identification from BigBite
Hadron Particle Identification
Gas Cherenkov and lead glass:
separate hadrons from electrons
Aerogel Cherenkov:
separates pions and other hadrons
• Kaon and proton data can be cleaned up by coincidence/TOF and the
RICH detector: both provide K/π ~ 4σ separation
• Combined pion rejection 99.9%
Particle Identification for Kaons
Polarized 3He Target
 Effectively a polarized neutron target
 Improved figure of merit
 Rb+K hybrid mixture cell
 Narrow bandwidth lasers
 Compact size: No cryogenic support needed
Beam
~90%
~1.5% ~8%
Performance of 3He Target
 High luminosity: L(n) = 1036 cm-2 s-1
 Record high steady ~ 60% polarization with 15 A
beam with automatic spin flip every 20 minutes
History of Figure of Merit of Polarized 3He Target
Average 3He pol. = 55%
19
Analysis: Target Single-Spin Asymmetry
Target single-spin asymmetry from normalized yields, need to consider :
beam charge, target density, DAQ life time, detector efficiency etc.
Automatic target spin
flip once every 20
minutes.
2845 target spin
“local pairs”
Beam Charge + vs
Beam Charge -
Beam charges are well-balanced
between the pairs
20
SSA check: HRS single-arm 3He SSA
(Witness channels on 3He, not corrected for target polarization and dilution)
K. Allada
Univ. of Kentucky
2010.
False asymmetry < 0.1%
Analysis of Asymmetry
 Two teams carried out independent analysis
 Red Team: Maximum Likelihood Method
 Blue Team: Local Pair-Angular Bin-Fit Method
 Do not share any code.
 Many cross checks on intermediate results.
Two team independent asymmetry analyses
Many cross checks on
intermediate asymmetries.
Red team.
Blue team.
Blue team implemented
Red team’s method.
3He
Target Single-Spin Asymmetry in SIDIS
3
He-(e, e'h), h = p +, p -
~87%
~8%
~1.5%
To extract information on neutron,
one would assume :
3
He- = 0.865 × n- - 2 ´ 0.028 × p3He
Collins SSA are not
large (as expected).
3He
Sivers SSA:
negative sign for π+,
consistent with zero for π-
After correction of N2 dilution (dedicated reference cell data)
Blue band: model (fitting) uncertainties
Red band: other systematic uncertainties
Results on Neutron
Collins
asymmetries are not
large, except at x=0.34
Sivers
agree with global fit, and
light-cone quark model.
Consistent with
HERMES/COMPASS
p + (ud ) favors negative
Independent
demonstration of
negative d-quark
Sivers function.
Blue band: model (fitting) uncertainties
Red band: other systematic uncertainties
Radiative correction: bin migration + uncer. of asy.
Spin-dependent FSI estimated <1% (Glauber
rescattering + no correction)
Diffractive rho: 3-10%
Paper on the arXiv
 arXiv: 1106.0363, will submit in a few days.
3He

ALT (DSA) Results
First measurement with 3He target
o
o
o
Ph.D. thesis of J. Huang (MIT 2011).
30 Hz beam helicity flips
Two independent analysis teams; cross checks
Corrected for small component of long. target spin, SL
 Data suggest non-zero SIDIS ALT: π-, +2.8σ (sum all bins)
g*
~7o
30o
h+/e’
3He
Spin
SL
e
BigBite
Preliminary
ST
PT
Higher twist contribution NOT included
Neutron ALT Extraction

 Corrected for proton dilution, fp
 Predicted proton asymmetry contribution < 1.5% (π+), 0.6% (π-)
n
 g1qT  D1hq , sensitive to d quark
 ALT
 Dominated by L=0 (S) and L=1 (P) interference
 Consist w/ model in signs, suggest larger asymmetry
Preliminary
Summary
 “Neutron Transversity” experiment (E06-010) completed.
 First measurement of Collins and Sivers moments (AUT) on 3He
 AUT results on neutron:
 Collins: π+ are π- asymmetries consistent with zero except at x ~ 0.34 for π+
 Sivers: π- is consistent with zero; however, π+ favor negative values
 Results to be submitted to PRL very soon
 First indication of a non-zero ALT: 3He→π-, +2.8σ ALT (sum all bins)
 Preliminary Kaon± Sivers and Collins moments are also available
 The neutron results combined with existing proton and deuteron data
will aid in constraining the d-quark sivers function
 JLab-12 GeV: Precision SSA measurements in SIDIS will be one
of the highlights as discussed in X. Qian’s thesis prize
presentation.
Jefferson Lab E06-010
Collaboration
Institutions
CMU, Cal-State LA, Duke, Florida International, Hampton, UIUC, JLab, Kharkov, Kentucky, Kent State,
Kyungpook National South Korea, LANL, Lanzhou Univ. China, Longwood Univ. Umass, Mississippi State, MIT,
UNH, ODU, Rutgers, Syracuse, Temple, UVa, William & Mary, Univ. Sciences & Tech China, Inst. of Atomic
Energy China, Seoul National South Korea, Glasgow, INFN Roma and Univ. Bari Italy, Univ. Blaise Pascal France,
Univ. of Ljubljana Slovenia, Yerevan Physics Institute Armenia.
Collaboration members
K. Allada, K. Aniol, J.R.M. Annand, T. Averett, F. Benmokhtar, W. Bertozzi, P.C. Bradshaw,
P. Bosted, A. Camsonne, M. Canan, G.D. Cates, C. Chen, J.-P. Chen (Co-SP), W. Chen,
K. Chirapatpimol, E. Chudakov, , E. Cisbani(Co-SP), J. C. Cornejo, F. Cusanno, M. Dalton,
W. Deconinck, C. de Jager, R. De Leo, X. Deng, A. Deur, H. Ding, C. Dutta, D. Dutta, L. El Fassi,
S. Frullani, H. Gao(Co-SP), F. Garibaldi, D. Gaskell, S. Gilad, R. Gilman, O. Glamazdin, S. Golge,
L. Guo, D. Hamilton, O. Hansen, D.W. Higinbotham, T. Holmstrom, J. Huang, M. Huang,
H. Ibrahim, M. Iodice, X. Jiang (Co-SP), G. Jin, M. Jones, J. Katich, A. Kelleher, A. Kolarkar,
W. Korsch, J.J. LeRose, X. Li, Y. Li, R. Lindgren, N. Liyanage, E. Long, H.-J. Lu, D.J. Margaziotis,
P. Markowitz, S. Marrone, D. McNulty, Z.-E. Meziani, R. Michaels, B. Moffit, C. Munoz Camacho,
S. Nanda, A. Narayan, V. Nelyubin, B. Norum, Y. Oh, M. Osipenko, D. Parno, J. C. Peng(Co-SP),
S. K. Phillips, M. Posik, A. Puckett, X. Qian, Y. Qiang, A. Rakhman, R. Ransome, S. Riordan,
A. Saha, B. Sawatzky,E. Schulte, A. Shahinyan, M. Shabestari, S. Sirca, S. Stepanyan, R. Subedi,
V. Sulkosky, L.-G. Tang, A. Tobias, G.M. Urciuoli, I. Vilardi, K. Wang, Y. Wang, B. Wojtsekhowski,
X. Yan, H. Yao, Y. Ye, Z. Ye, L. Yuan, X. Zhan, Y. Zhang, Y.-W. Zhang, B. Zhao, X. Zheng, L. Zhu,
X. Zhu, X. Zong.
Experimental Extraction of g1T
 Extractable from
Double Beam-Target Spin Asymmetry (DSA) in SIDIS with
transversely polarized target: ALT
e’
e
n
X
π
cos(h s )
ALT


h

cos(h  s ) q
d

d


d

s

h
2

g

D


1T
1q
h


d

d


d

 s
Existing ALT Results
 COMPASS
COMPASS
Proton arXiv:1012.0155 [hep-ex]
 Last Session, C. Schill
 Proton , Deuteron
 HERMES
 Last Session, L. Pappalardo
 Jlab E06-010
 This talk
 Pol. 3He Target (eff. pol. n)
 Fast beam helicity flips
Deuteron
Eur. Phys. J. Special Topics 162, 89–96 (2008)
Transversity Data Analysis Flow
Raw Data
Run
data base
Spectrometer Detector
Scalers
optics
calibration
Target
polarization
Farm
Production
PID cuts
Event
Selection
Reconstruction
Cuts
Beam Cuts
Lumi Cuts
…
Two independent teams: Blue vs Red
Witness
Asymmetry
Coincidence
Asymmetry
Physics
Analysis
Corrections: luminosity,
DAQ deadtime, detector efficiency, ….
N2 Dilution
correction
Background
Separation of
Collins vs Sivers
3He
to neutron
correction
Correction for N2 Dilution
Cross section ratios
determined through
reference cell N2 and
3He data.
From 3He to Neutron
very small (< 0.003)
Cross section ratios determined
through reference cell H2 and 3He
data.
DSA Consistency Checks
• MLE vs Local Spin Pair Methods