tmd study at jlab : results and future
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TMD Study at JLab: Results and Future
J. P. Chen , Jefferson Lab PacificSPIN-13, Jinan, China, October 28-31, 2013
TMDs with 6 GeV JLab: Exploration Results from Hall C: PT dependence of unpolarized flavor PDFs Results from Hall B (CLAS6)
PT dependence of spin asymmetry A1
SSA with longitudinal target or beam Recent and preliminary results Hall A (transversely Polarized 3He (n))
Collins/Sivers/Worm-gear asymmetries on pions and Kaons Inclusive hadron and electron SSA
JLab 12 GeV Plan for TMD study: Precision Multi-d Mapping SoLID Program on TMDs TMD program in Hall B (CLAS12) and C
Jefferson Lab at a Glance
~ 1400 Active Users ~ 800 FTEs 178 Completed Experiments
@ 6 GeV Produces ~1/3 of US PhDs
in Nuclear Physics A B C
CEBAF High-intensity electron
accelerator based on CW SRF technology
Emax = 6 GeV Imax = 200 mA Polmax = 85%
A B C
12 GeV
Wpu(x,kT,r ) Wigner distributions
d2kT
PDFs f1
u(x), .. h1u(x)
GPDs/IPDs
d2kTd2rT
TMD PDFs
f1u(x,kT), ..
h1u(x,kT) 3D imaging
5D Dist.
Form FactorsGE(Q2), GM(Q2)
d2rT dx &Fourier Transformation
1D
Unified View of Nucleon Structure
Quark polarization
Unpolarized(U)
Longitudinally Polarized (L)
Transversely Polarized (T)
Nucleon Polarization
U
L
T
Leading-Twist TMD PDFs
f1 =
f 1T =
Sivers
Helicityg1 =
h1 =Transversity
h1 =
Boer-Mulders
h1T =
Pretzelosity
g1T =
Worm Gear
h1L =
Worm Gear
: Probed with transversely pol targetHERMES, COMPASS, JLab E06-010
Nucleon Spin
Quark Spin
Scattering Plane
Gold mine for TMDs Access all eight leading-twist TMDs
through spin-comb. & azimuthal-modulations
Tagging quark flavor/kinematics
Tool: Semi-inclusive DIS (SIDIS)
Unpolarized TMDsTest x-z Factorization Flavor PT Dependence
JLab Hall C SIDIS Results
From Form Factors to Transverse Densities
up quark down quarkby
bxbx
by
Unpolarized TMD: Flavor PT Dependence?
A. Bacchetta, Seminar @ Jlab, arXiv1309.3507 (2013)
up quark down quarkky
ky
kxkx
Flavor PT Dependence from Theory Chiral quark-soliton model (Schweitzer, Strikman, Weiss, JHEP, 1301
(2013) sea wider tail than valanee
• Flagmentation model, Matevosyan, Bentz, Cloet, Thomas, PRD85 (2012) unfavored pion and Kaon wider than favored pion
f1u/f1d
kT
Hall C Results: Flavor PT Dependence
C
(md)2
(mu)2
(m-)2
(m+)2
Results: from JLab Hall B (CLAS6)
PT Dependence of A1
SSA in Longitudinal TargetSSA in Longitudinal Beam(plots courtesy of Harut Avagyan)
A1 PT-dependence
CLAS data suggests that width of g1 is less than the width of f1
Lattice
PT
arXiv:1003.4549 A
1
B.Musch et al arXiv:1011.1213
Kotzinian-Mulders Asymmetries
KM-TMD unique (no analog in GPDs)
HERMES
CLAS (5days)
B.Musch arXiv:0907.2381
<kx> = −60(5) MeV for down quarks <kx> = 16(5) MeV for up quarks
B. Pasquini hep-ph/0806.2298
SSA for longitudinally polarized target
sinf asymmetry for long.pol. target are comparable for p0 & p+ while p- SSA seem to have an opposite sign indicating significant Collins type contribution.
Kotzinian et al (1999) hep-ex/0104005
CLAS PRELIMINARY
Efremov et al (2001) Zhun Lu et al (2013)
SSA for longitudinally polarized beam
ALU CLAS @4.3 GeV (2003)
Efremov et al (2003)
The force on a quark polarized in the x-direction with kT in the y-direction right after scattering Burkardt (2008),Qiu(2011)
W. Mao, Z. Lu (arXiv:1210.4790)
W. Gohn
CLAS 5.5 GeV
Sivers type contribution may dominate the p0 SSAsCollins type contribution seem to dominate the p-SSA
CLAS 5.7 GeV(p0)
Single Spin Asymmetries with A Transversely Polarized 3He (n)
JLab Hall A E06-010Published and Preliminary Results
From SIDIS and Inclusive Reactions
SIDIS: Separation of Collins, Sivers and pretzelocity effects through angular dependence
1( , )
sin( ) sin( )
sin(3 )
l lUT h S
h SSiverCollins
Pretzelosi
UT
tyU
sUT h S
h ST
N NAP N
A
ANA
f f f f
f f
-
+ + + -
+ -
1
1 1
1
1 1
sin( )
sin(3 )
sin( )Co
PretzelosityU
SiversUT
llins
T h S T
h S
UT
UT h S
TU
UT
TA
H
f
A
D
A h H
h
f
f
f
f f
f
-
+
-
E06 010 Experiment‑
• First measurement on n (3He)• Transversely Polarized 3He Target• Polarized Electron Beam, 5.9 GeV
• BigBite at 30º as Electron Arm– Pe = 0.7 ~ 2.2 GeV/c
• HRSL at 16º as Hadron Arm– Ph = 2.35 GeV/c – Excellent PID for p/K/p
18
Beam Polarimetry(Møller + Compton)
LuminosityMonitor
XKeeHe ),(3 7 PhD Thesis Students (graduated) + 2 new students
3He (n) Target Single-Spin Asymmetry in SIDIS
-+ pp ,),',(n hhee
neutron Sivers SSA:negative for π+, Agree with Torino Fit
neutron Collins SSA small Non-zero at highest x for p+
Blue band: model (fitting) uncertainties Red band: other systematic uncertainties
E06-010 collaboration, X. Qian at al., PRL 107:072003(2011)
Asymmetry ALT Result
• neutron ALT : Positive for p- • Consist w/ model in signs, suggest larger asymmetry
hq
qTLT DgFA shsh
11)cos()cos(
LT -- ffff
To leading twist:
J. Huang et al., PRL. 108, 052001 (2012).
Worm-Gear
Dominated by L=0 (S) and L=1 (P) interferenceTrans helicity
Pretzelosity Results on NeutronExtracted Pretzelosity Asymmetries, For both p+ and p-, consistent with zero within uncertainties.
Preliminary Results
In models, directly related to OAM,L=0 and L=2 interference
Analysis by Y. Zhang (Lanzhou) and X. Qian (Caltech)
E06-010: Inclusive Hadron SSA (AN)
• Clear non-zero vertical target SSA • Opposite sign for p+ and p-
• Large for K+
0 hN PxlS
0sin 90=A SS
UT
Preliminaryvertical target
ShNUT PxlSσ sin∼
Analysis by K, Allada (JLab), Y. Zhao (USTC)
E06-010: Inclusive Hadron SSA (AN)
• Clear non-zero target SSA • Opposite sign for p+ and p-
• AN at low pT not very well understood• Results consistent with
predictions based on Sivers mechanism (valid at high pT )
0 hN PxlS
0sin 90=A SS
UT
Preliminary
Preliminary
vertical target
Inclusive Target Single Spin Asymmetry: DIS
3Heθ
e-
• Unpolarized e- beam incident on 3He target polarized normal to the electron scattering plane.
• However, Ay=0 at Born level, sensitive to physics at order α2; two-photon exchange.
Ay (Q2) -
+
• In DIS case: related to integral of Sivers• Physics Importance discussed in A. Metz’s paper
Inclusive Target Single-Spin Asymmetry
Extracted neutron SSA from 3He(e,e’) Vertically polarized target
• Results show 2-photon effects
• Consistent with A. Metz’s prediction: 2-photon interact with 2 quarks and q-g-q correlator from Torino fit for Sivers (solid black)
• Disagree with predictions based on KQW q-g-q correlator (red-dashed)
• Disagree with predictions based on 2-photon interact with 1 quark (blue dashed)
Analysis by J. Katech(W&M), X. Qian (Caltech)
Future: TMD study 12 GeV JLab
Precision Study of TMDsIn the Valence Quark Region
H2 D2
Hall C/SHMSL-T studies, precise p+/p- ratios
3He, NH3
Hall A/SBSHigh x - Q2, 2-3D
Hall A/SOLIDHigh Lumi and acceptance – 4D
U L TqN
U
L
T H2/D2,NH3/ND3, HD
Hall B/CLAS12General survey, medium luminosity
Multi-Halls SIDIS Program
SoLID for SIDIS/PVDIS with 12 GeV JLab•Exciting physics program:
Five approved experiments: three SIDIS “A rated”, one PVDIS “A rated”, one J/Psi “A- rated”
•International collaboration: eight countries and 50+ institutions
•GEMs for tracking •Cherenkov and EM
Calorimeter for electron PID •Heavy Gas Cherenkov and
MRPC (TOF) for pion PID
•CLEOII Magnet (official)•Draft pCDR just completed
E12-10-006/E12-11-108, Both Approved with “A” Rating Mapping of Collins(Sivers) Asymmetries with SoLID
• Both p+ and p-• Precision Map in
region x(0.05-0.65)
z(0.3-0.7) Q2(1-8) PT(0-1.6)
• <10% d quark tensor charge
Collins (Sivers) Asymmetries
Expected Improvement: Sivers Function
• Significant Improvement in the valence quark (high-x) region• Illustrated in a model fit (from A. Prokudin)
f 1T =
E12-11-107: Worm-gear functions (“A’ rating: )
• Dominated by real part of interference between L=0 (S) and L=1 (P) states
• No GPD correspondence• Lattice QCD -> Dipole Shift in mom. space.• Model Calculations -> h1L
=? -g1T .
h1L =
g1T =
Longi-transversityTrans-helicity
Cent
er o
f poi
nts:
)()(~ 11 zDxgA TLT )()(~ 11 zHxhA LUL
Summary on SoLID TMD Program• Unprecedented precision 4-d mapping of SSA
• Collins, Sivers, Pretzelosity and Worm-Gear• Both polarized 3He (n) and polarized proton with SoLID• Three “A” rated experiments approved. One LOI on di-hadron.• Study factorization with x and z-dependences • Study PT dependence• Combining with the world data
• extract transversity and fragmentation functions for both u and d quarks• determine tensor charge• study TMDs for both valence and sea quarks • learn quark orbital motion and quark orbital angular momentum• study Q2 evolution
• Global efforts (experimentalists and theorists), global analysis• much better understanding of multi-d nucleon structure and QCD
• Welcome new collaborators
Summary
• Nucleon Spin and TMD study have been exciting and fruitful• Recent and Preliminary Results from JLab with transversely polarized
targets: g2, TMDs • JLab 12 GeV Planned SoLID program with JLab12
Precision 4-d mapping of TMD asymmetries• Longer-term future: EIC in US, China and Europe
Exciting new opportunities
Precision experimental data + development in theory for Nucleon TMDs +… lead to breakthrough in understanding QCD?
Backup Slides
High Luminosity polarize target: L(n) = 1036 cm-2 s-1(achieved), 1037 cm-2 s-1 (R&D) Compact size: No cryogenic support needed Proton dilution measured experimentally
Polarized 3He Target
BeamPolarimetry
LuminosityMonitor
Beam
3HeCell
~90% ~1.5% ~8%
High luminosity: L(n) = 1036 cm-2 s-1
Record high 50-65% polarization in beam with automatic spin flip / 20min <P> = 55.4% ± 0.4% (stat. per spin state) ± 2.7 % (sys.)
Performance of 3He Target
E06-010 3He Target Single-Spin Asymmetry in SIDIS
3He Sivers SSA:negative for π+,
3He Collins SSA small Non-zero at highest x for p+
Blue band: model (fitting) uncertainties Red band: other systematic uncertainties
X. Qian at al., PRL 107:072003(2011)
Asymmetry ALT Result
• 3He ALT : Positive for p-
hq
qTLT DgFA shsh
11)cos()cos(
LT -- ffff
To leading twist:
J. Huang et al., PRL. 108, 052001 (2012).
Worm-Gear.
Inclusive Hadron Electroproduction
e + N↑ h + X (h = p, K, p)
Why a non-zero AN is interesting? – Analogues to AN in collision – Simpler than due to only one quark channel – Same transverse spin effects as SIDIS and p-p collisions (Sivers, Collins, twist-3)– Clean test TMD formalism (at large pT ~ 1 GeV or more)– To help understand mechanism behind large AN in in the TMD framework
pT
pp↑→hX
SsinUTTFN A=p,xA
pp↑→ hX
pp↑→ hX
ShNUT PxlSσ sin∼
Transverse SSA in Inclusive Hadron
• Target spin flip every 20 minutes• Acceptance effects cancels • Overall systematic check with AN at ϕS= 0
– False asymmetry < 0.1%
0sin =A SS
UT
-N+NNN=A S
UTsin
p+ p-
False Asymmetry
0=PxlS hN
Preliminary
JLab 12 GeV Upgrade
Maintain capability to deliver lower pass beam energies : 2.2, 4.4, 6.6,….
Enhanced capabilities in existing HallsIncrease of Luminosity 1035 - ~1039 cm-2s-1
The completion of the 12 GeV Upgrade of CEBAF was ranked the highest priority in the 2007 NSAC Long Range Plan. New Hall
CHL-2
20 cryomodules
Add 5 cryomodules
Add 5 cryomodules
20 cryomodules
Add arc
JLab Physics Program at 12 GeV
43
Hall C – precision determination of valence quark properties in nucleons and nuclei
high momentum spectrometers & dedicated equipments
Hall B - 3-D nucleon structure via GPDs & TMDs Search new form of hadron. matter via Meson Spectr.
4p detector
Hall A – form factors, GPDs & TMDs , SRCLow-energy tests of the SM and Fund. Symmetry Exp
SoLID, MOLLER.
High luminosity, high resolution & dedicated equipments
Hall D - exploring origin of confinement by studying exotic mesons using real photons
Hermetic detectorPhoton tagger
Hall A
Hall B
Hall C
Hall D
Map Collins and Sivers asymmetries in 4-D (x, z, Q2, PT)
Access transversity in transversely polarized neutron target through π+ π- di-hadron production
Run simultaneously with SIDIS 3He (e,e’π±)X
Systematical check of two approaches to access h1
New : LOI – Dihadron in DIS on 3He
Asymmetry projection for one M-z bin
Green (Blue) Points: SoLID projections for polarized NH3 (3He/n) targetLuminosity: 1035 (1036) (1/cm2/s); Time: 120 (90) days
Black points: EIC@HIAF projections for 3 GeV e and 12 GeV pLuminosity: 4 x 1032 /cm2/s; Time: 200 days
The TMD simulation: Projections for SIDIS Asymmetry π+
Hiayan Gao (Duke)
EIC@HIAF reach high precision similar to SoLID at lower x, higher Q2 region
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