Post on 21-Feb-2021
Spin Physics at JLab
Seonho ChoiSeoul National University
June 20, 2011
PacSPIN 2011 Cairns, Australia
Contents
• QCD and Spin
• Inclusive DIS
• Semi-Inclusive DIS
• Some results from Jefferson Lab
• Future - Upgrade and EIC
• Summary
Quarks, Gluons & QCD
• Asymptotic freedom to Non-perturbative region
• One of the major challenges in current nuclear physics
• Spin structure is one of important tests.
Nucleon Spin Structure
• Explaning nucleon spin in terms of quarks and gluons (QCD)
• Nucleon spin is 1/2
• De-composition is not trivial
Nucleon Spin Pizza
Ji Jaffe & Manohar
Only common to both decompositions!
More on the decomposition,Cho’s Talk
Today 11:40
Nucleon Spin Structure
• Explaining nucleon spin in terms of quarks and gluons (QCD)
• Nucleon spin is 1/2
• De-composition is not trivial
• ~30% from quark spins
• Little or no polarized gluons
Solving the Puzzle
• Spin structure functions g1 and g2
• Electron scattering on polarized targets (p, d, 3He)
• Gluon polarization
• Direct measurement from polarized pp scattering (PHENIX, STAR)
• QCD evolution from spin structure functions
• Orbital Angular Momentum (OAM)
• Partly from Generalized Parton Distributions
Related Talks
• Fields (Next talk) OAM at RHIC
• Okada (11:00) Delta G at PHENIX
• Wakamatsu (12:20) OAM extraction
Polarized DIS
• Deep Inelastic Scattering
• with polarized electron beams
• and polarized targets
• Probes spin states of the quarks
• Spin structure functions, g1 and g2
• 2 different target polarization directions
Spin Structure Functions
• g1 : easy to understand, relatively easy to measure
• g2 : more complex
• g2 = 0 in naive quark model
• sensitivity with target polarization perpendicular to beam polarization
g2 and Higher Twists
• Decomposition of g2
a twist-2 term (Wandzura & Wilczek, 1977):
a twist-3 term with a suppressed twist-2 piece (Cortes, Pire & Ralston, 1992):
Twist -2 Twist -3+1
+1/2
0
-1/2
Transversity !"#correlations
!" #$%&'(#)*+,-(.$&/.))0-#12.$3
45#6&730)&,).(8&90012$!:&;0<8.)1&;0<3:&=> !"4($0&?@:&"AAB
g2 and quark-gluon correlations
• a twist-2 term (Wandzura-Wilcek)
• a twist-3 term with a suppressed twist-2 piece
Transversity
qg correlations
Color Polarizability d2• 2nd moment of g2-g2
WW
d2: twist-3 matrix element
d2 and g2-g2WW: clean access of higher twist (twist-3) effect: q-g correlations
Color polarizabilities χΕ,χΒ are linear combination of d2 and f2 Provide a benchmark test of Lattice QCD at high Q2
Avoid issue of low-x extrapolation
Relation to Sivers and other TMDs?
d2(Q2)
very prelimGREEN: E97-110. (Hall A, 3He)
RED : RSS. (Hall C, NH3,ND3)
BLUE: E01-012. (Hall A, 3He)
Proton
Neutron
“d2n” completed in Hall A,more details in Chen’s talk
3-D Description in Momentum Space
• Transverse Momentum-dependent parton Distributions (TMD’s)
!"#$% &'(#$)*#+)',
-, .'(#$)*/0 1',2)+"0),#((3 .'(#$)*/0 4$#,56/$5/(3 .'(#$)*/0
!"#$%&'
(&$)*+,)-+&'
.
/
0
7(( 1/#0),2 48)5+ 49:5
! ;4 <
!; <
"; <
";4 <
#;1 <
#; <
#;4 <
#;4 <
4$#,56/$5)+3
='/$ 9"(0/$
.$/+*/('5)+3>)6/$5
?/()@)+3
!"#$%&' 12+'3")*4 12+'
!"#$% &'(#$)*#+)',
-, .'(#$)*/0 1',2)+"0),#((3 .'(#$)*/0 4$#,56/$5/(3 .'(#$)*/0
!"#$%&'
(&$)*+,)-+&'
.
/
0
7(( 1/#0),2 48)5+ 49:5
! ;4 <
!; <
"; <
";4 <
#;1 <
#; <
#;4 <
#;4 <
4$#,56/$5)+3
='/$ 9"(0/$
.$/+*/('5)+3>)6/$5
?/()@)+3
!"#$%&' 12+'3")*4 12+'
Accessing TMD’s!""#$$ %&'$ ()*+,-) ./*0 1*+"#$$#$
Partonic scattering amplitude
Fragmentation amplitude
Distribution amplitude
proton
lepton lepton
pionproton
proton lepton
antilepton
Drell-Yan
!"#$%&'(
)"&#
EIC
SIDIS
electron
positron
pion
pion
e–e+ to pions * *+,-.-,/ +.0/h h
!""#$$ %&'$ ()*+,-) ./*0 1*+"#$$#$
Partonic scattering amplitude
Fragmentation amplitude
Distribution amplitude
proton
lepton lepton
pionproton
proton lepton
antilepton
Drell-Yan
!"#$%&'(
)"&#
EIC
SIDIS
electron
positron
pion
pion
e–e+ to pions * *+,-.-,/ +.0/h h
!""#$$ %&'$ ()*+,-) ./*0 1*+"#$$#$
Partonic scattering amplitude
Fragmentation amplitude
Distribution amplitude
proton
lepton lepton
pionproton
proton lepton
antilepton
Drell-Yan
!"#$%&'(
)"&#
EIC
SIDIS
electron
positron
pion
pion
e–e+ to pions * *+,-.-,/ +.0/h h
!""#$$ %&'$ ()*+,-) ./*0 1*+"#$$#$
Partonic scattering amplitude
Fragmentation amplitude
Distribution amplitude
proton
lepton lepton
pionproton
proton lepton
antilepton
Drell-Yan
!"#$%&'(
)"&#
EIC
SIDIS
electron
positron
pion
pion
e–e+ to pions * *+,-.-,/ +.0/h h
SIDIS
e+e-
Drell-Yan
SIDIS!""#$$%&'()*+%,-$)(-./)-*+$%)0(*/10%2#3-4
5+"6/$-7#%,52
!!!"#$%&'()*
!!!")*
!!!"$+',-(
!!!$($',-(
$',-(*
!!!"$.',-(*
!!!$.%&'(
!!!/$)(.
$%&'(.
.
$+',-(
$',-(
$',-(
$.',-(
$.%&'(
0
.
.
.
.
Sh
Sh
Sh
Sh
h
h
LTSheT
LLeL
UTSh
ULSh
UTShT
ULhL
UUh
TUU
hhS
FS
FS
F
F
FS
FS
F
F
yxyQdPdzddxdyd
d
!"#$%&'()*+
,$%&'()*+-&'.*/
,$%&'()*+0*&1&"+-&'.*/
!2! !-" #$%&'( )*+$%,-$(,*./ "" 0'$1 )*+$%,-$(,*.
0$*' 34%+*'
5(6*'7
-'&"76*'7(/8
,'*/)*%$7(/8
!""#$$%&'()*+%,-$)(-./)-*+$%)0(*/10%2#3-45+"6/$-7#%,52
!!!"#$%&'()*
!!!")*
!!!"$+',-(
!!!$($',-(
$',-(*
!!!"$.',-(*
!!!$.%&'(
!!!/$)(.
$%&'(.
.
$+',-(
$',-(
$',-(
$.',-(
$.%&'(
0
.
.
.
.
Sh
Sh
Sh
Sh
h
h
LTSheT
LLeL
UTSh
ULSh
UTShT
ULhL
UUh
TUU
hhS
FS
FS
F
F
FS
FS
F
F
yxyQdPdzddxdyd
d
!"#$%&'()*+
,$%&'()*+-&'.*/
,$%&'()*+0*&1&"+-&'.*/
!2! !-" #$%&'( )*+$%,-$(,*./ "" 0'$1 )*+$%,-$(,*.
0$*' 34%+*'
5(6*'7
-'&"76*'7(/8
,'*/)*%$7(/8
!""#$$%&'()*+%,-$)(-./)-*+$%)0(*/10%2#3-45+"6/$-7#%,52
!!!"#$%&'()*
!!!")*
!!!"$+',-(
!!!$($',-(
$',-(*
!!!"$.',-(*
!!!$.%&'(
!!!/$)(.
$%&'(.
.
$+',-(
$',-(
$',-(
$.',-(
$.%&'(
0
.
.
.
.
Sh
Sh
Sh
Sh
h
h
LTSheT
LLeL
UTSh
ULSh
UTShT
ULhL
UUh
TUU
hhS
FS
FS
F
F
FS
FS
F
F
yxyQdPdzddxdyd
d
!"#$%&'()*+
,$%&'()*+-&'.*/
,$%&'()*+0*&1&"+-&'.*/
!2! !-" #$%&'( )*+$%,-$(,*./ "" 0'$1 )*+$%,-$(,*.
0$*' 34%+*'
5(6*'7
-'&"76*'7(/8
,'*/)*%$7(/8
Separation via Angular Dependence!"#$%$&'()*(+*,(--')./*!'0"%.*$)1*#%"&2"-(3'&4*"++"3&.*&5%(675*$)76-$%*1"#")1")3"
!" # $
%&'" $ %&'" $
%&'"( $
l lUT h S
h SSiverCollins
Pretzelosi
UT
tyU
sUT h S
h ST
N NAP N
A
ANA
!
! !
!
! !
%&'" $
%&'"( $
%&'" $Co
PretzelosityU
SiversUT
llins
T h S T
h S
UT
UT h S
TU
UT
TA
H
f
A
D
A h H
h
)*+*),))-%,./0/'.,1',23+,456&578/%,"9#,:;#,<,5'.,=>$
?56@/,5'@A856,B14/65@/,5'.,06/B&%&1',C/5%A6/C/'D,1E,5%FCC/D6&/%,
&',23+,0G5%/,%05B/,&%,/%%/'D&58H,
d2kT
PDFs q(x), Δq(x)…
d2rT Spin and longitudinal momentum correlations with kT and rT lead to observable effects in exclusive and semi-inclusive processes
TMD PDFs q(x,kT), Δq(x,kT)…
GPDs H(x,rT), H~(x,rT)…
Structure of the Nucleon
d2k T
Wpu(k,rT) “Mother” distributions (Wigner, GTMDs,..)
d2r T
The Machine
Jefferson Labat a Glance
• Electron linear accelerator
• Beam energy up to ~ 6 GeV
• 12 GeV upgrade in progress
• Beam polarization over 80%
• 100% duty cycle, continuous beam
• 3 Experimental Halls: A, B and C
Jefferson Lab
Jefferson Lab
An aerial view of the recirculating linear accelerator
and 3 experimental halls.
Cryomodules in the accelerator tunnel
Superconducting radiofrequency (SRF) cavities undergo vertical testing.
CEBAF Large Acceptance Spectrometer (CLAS) in Hall B
Inclusive DIS at JLab
Valence A1p and A1n
Hall B CLAS, Phys.Lett. B641 (2006) 11 Hall A E99-117, PRL 92, 012004 (2004) PRC 70, 065207 (2004)
Effect of OAMPolarized DIS and Nucleon Spin Structure
H. Avakian, S. Brodsky, A. Deur, F. Yuan, Phys. Rev. Lett.99:082001(2007)
Figure credit: A. Deur
First Moments of g1p and g1n
EG1b, arXiv:0802.2232 EG1a, PRL 91, 222002 (2003)
E94-010, from 3He, PRL 92 (2004) 022301 E97-110, from 3He, EG1a, from d-p
Test fundamental understanding ChPT at low Q2, Twist expansion at high Q2, Future Lattice QCD
Precision Measurement of g2n
• Measure higher twist → quark-gluon correlations.• Hall A Collaboration, K. Kramer et al., PRL 95, 142002 (2005)
SANE at Hall-C
• Beam: polarized electron beam (Jefferson Lab) at 4.7 and 5.9 GeV
• Target: Polarized NH3 target
• Polarization: ~67%
• Orientation: parallel (0o) or “perpendicular” (80o)
• Scattering angle: 40o
• Detectors: BETA and HMS of Hall-C
Setup
SetupTargetPolarized NH3
with 5T field
Setup
BeamlineChicaneHe bag
SetupElectron ArmTrackerCerenkovLuciteBigCal
Setup
HMSPacking fractionsMonitoring
Big Electron Telescope Array
Big Electron Telescope Array
Forward Tracker
Big Electron Telescope ArrayCerenkov
Big Electron Telescope ArrayLucite Hodoscope
Big Electron Telescope ArrayBigCal
Analysis in Progress0.3 0.4 0.5 0.6 0.7 0.8 0.9 1-0.15
-0.1
-0.05
0
0.05
0.1
0.15
0.2
0.25
g1p g2ww AAC g1p_TM AAC g2WW_TM
0.25 0.35 0.45 0.55 0.65 0.75 0.85-0.6
-0.5
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
AAC g1p_TM AAC g2WW_TM SANE g1 SANE g2
PRELIMIN
ARY
SIDIS at JLab
SIDIS at Hall-A!"#$%&'()'*'%&+,-./0-12%
• !"#$%&'() *+( ,$%-(./ 0 123
4&.5 6($7/ 4"%#) %(8"%)
• !"#$%&'() 9#(8.%": ;($7
– !"#$%!"#$%&'$.&":– <$=. <#&>>&:- $. &#'(– ))* ?(@(# A5$%-( B=C77(.%C
8":.%"##() 6C ":#&:( D(() 6$8E
• ;&-;&.( $. *2F $= 9#(8.%": B%7– !" G 2HI J KHK L(MN!
• +OP? $. Q1F $= +$)%": B%7– !# G KH*R L(MN!
+,
-./0%)12/340.5367*822.3%9%:10;51<=
>?04<1@456*1<4513
3455#$4.#2/41%/16578-9%:#%#18%:#4%;.47,9%#2%<=>
Neutron Single-‐Spin AsymmetryPreliminary Collins
asymmetries are not large, except at x=0.34
Siversagree with global fit, and light-‐cone quark model.
favors negaEve.
u-‐quark in neutron favors negaEve.by SU(2):d-‐quark in proton favors nega9ve.
36
• Worm-‐gear TMD, g1T ⊗ D1
–Dominated by L=0 (S) and L=1 (P) interference.
• Consist with model in sign.suggest a larger asymmetry.
Neutron Double-‐Spin Asymmetry ALT
Preliminary
37
More details on Spin Physics from Hall-AChen’s Talk
Thursday 16:20
CLAS configurations
π−
e
π+
ep→e’πX
Polarizations:Beam: ~80%NH3 proton 80%,ND3 ~30%HD (H-75%,D-25%)
1) Polarized NH3/ND3 (no IC, ~5 days)2) Unpolarized H (with IC ~ 60 days)3) Polarized NH3/ND3 with IC 60 days
10% of data on carbon 4) Polarized HD-Ice (no IC, 25 days)
Unpolarized, longitudinally and transversely polarized targets
Unpolarized and longitudinally polarized targets
0.05 K0.6 K
1 K4K Inner CalorimeterHD-Ice
Scattering of 5.7 GeV electrons off polarized proton and deuteron targets
SIDIS with JLab at 6 GeV
DIS kinematics, Q2>1 GeV2, W2>4 GeV2, y<0.85 0.4>z>0.7, MX
2>2 GeV2
2
eπX
Large PT range and full coverage in azimuthal angle φ crucial for studies
A1 PT-dependence in SIDIS
M.Anselmino et al hep-ph/0608048
π+ A1 suggests broader kT distributions for f1 than for g1
π- A1 may require non-Gaussian kT-dependence for different helicities and/or flavors
μ02=0.25GeV2
μD2=0.2GeV2
0.4<z<0.7
arXiv:1003.4549
A1
A1 PT-dependence
CLAS data suggests that width of g1 is less than the width of f1
AnselminoCollins
Lattice
PT
PT
arXiv:1003.4549
~10% of E05-113 data
Longitudinal Target SSA measurements at CLAS
p1sinφ+p2sin2φ
0.12<x<0.48
Q2>1.1 GeV2
PT<1 GeV
ep→e’πX
W2>4 GeV2
0.4<z<0.7
MX>1.4 GeV
y<0.85
p1= 0.059±0.010p2=-0.041±0.010
p1=-0.042±0.015p2=-0.052±0.016
p1=0.082±0.018p2=0.012±0.019
CLAS-2009 (E05-113)CLAS PRELIMINARY
CLAS-2000
Data consistent with negative sin2φ for π+
JLab 12GeV UpgradeJLab Upgrade to 12 GeV
CHL-2
Enhance equipment in existing halls
Add new hall
!"#$%&'()*"+&"'$&,$-.+),/$0,."+1(.&),$-"(.)+2
3+"(&'&),$4"1'5+"6",.$7+),.&"+8-"1+(9$:)+$,"#8$";).&($<=%$'.1."'$1,>$61.."+$
Add new hall
12 GeV Science Program
• The physical origins of quark confinement (GlueX, meson and baryon spectroscopy)
• The spin and flavor structure of the proton and neutron (PDF’s, GPD’s, TMD’s)
• The quark structure of nuclei
• Probe potential new physics through high precision tests of the Standard Model
Projections for JLab at 12 GeV
A1n
A1p
Solenoidal Detector for SIDIS (Hall-A)
!"#$
%$&'()*(+,-*./&0*123*456,-&7*89:;<
!"#$%&$'()&*+",&-./&0($&102102&304()"5&6-./&5,'*(&,)2)7
89:)2+3)("&8;<=;>=>>?
Projected Data!"#$%&'%( )*'*• +#'*, -.// 0123 12 45 !' *2( 6 7#" --89:9 ;%< 0%*=:• 6 "*2>%3 7"#= /:? @ /:A5 #2,B * 3C0 "*2>% #7 --89:9 ;%< 3D#E2 D%"%:
For more details,Meziani’s Talk
Thursday 17:00
Summary• Polarized DIS
• Extensive measurements for non-perturbative region
• longitudinal target: Halls A, B and C
• transverse target: Halls A and C
• SIDIS
• Start of the program at 6 GeV
• More to come after 12 GeV upgrade
• GPD’s
• Towards full understanding of nucleon structure
• EIC will be an ideal upgrade to the next frontier of QCD