studies of partonic structure using sidis
DESCRIPTION
Studies of Partonic Structure using SIDIS. H.Avakian (JLab). Hall-C collaboration meeting, JLab, Jan 22. Outline. Describe the complex nucleon structure in terms of partonic degrees of freedom of QCD. Transverse Momentum Distributions (TMDs) of quarks - PowerPoint PPT PresentationTRANSCRIPT
JLab, Jan 20101
Studies of Partonic Structure using SIDISStudies of Partonic Structure using SIDIS
H.Avakian (JLab)H.Avakian (JLab)
Hall-C collaboration meeting, JLab, Jan 22Hall-C collaboration meeting, JLab, Jan 22
JLab, Jan 201022
Outline
Describe the complex nucleon structure in terms of partonic degrees of freedom of QCD
•Transverse Momentum Distributions (TMDs) of quarks •Spin and spin-azimuthal asymmetries in semi-inclusive DIS
– Tests of partonic description
– Spin-azimuthal asymmetries
– Double spin asymmetries– Future measurements– From JLab12 → EIC
•Summary
JLab, Jan 20103
Transverse Momentum Dependent (TMD) Distributions
Quark polarization
Nucleon polarization
Real and imaginary parts of the L≠0 interference contributions
Factorization of kT-dependent PDFs proven at low PT of hadrons (Ji et al)
Twist-2
Twist-3
f1u(x,kT)
JLab, Jan 20104
SIDIS kinematical plane and observables
Beam polarization Target polarization
U unpolarized
L long.polarized
T trans.polarized
sin2moment of the cross section for unpolarized beam and longitudinal target
JLab, Jan 201055
s
x
h
PT
Fragmenting quark polarization
C
C
y
x
S h
PTS = +h
x
PT
h
S=y
HT function related to force on the quark. M.Burkardt (2008)
Collins mechanism for SSACollins mechanism for SSAfragmentation of transversely polarized quarks into unpolarized hadrons
JLab, Jan 201066
Sivers mechanisms for SSASivers mechanisms for SSA -Correlation between quark transverse momentum and the proton spin
S
x
kT
PT
Proton polarization
S
HT asymmetries (T-odd)
No leading twist, provide access to quark-gluon correlations
JLab, Jan 201077
SIDIS: partonic cross sections
kT
PT = p┴ +z kT
p┴
JLab, Jan 20108
Double spin asymmetries and flavor decomposition
Anti-parallel electron & quark spins
Parallel electron & quark spins
u-quarks are mainly aligned with proton spin (u>0)
HERMES
JLab, Jan 201099
Scattering of 5.7 GeV electrons off polarized proton and deuteron targets
SIDIS with JLab at 6 GeVSIDIS 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
eX
Large PT range and full coverage in azimuthal angle crucial for studies
JLab, Jan 201010
Cell: Astral Cell: Maureen
e
e’
HRSL
BigBite
16o
30o
Polarized3He Target
Target Single-Spin Asymmetry in Semi-Inclusive n↑(e, e’+/-)
pt ~ 65% (proposal 42%)
• First measurement of the neutron Collins and Sivers asymmetries in SIDIS.
• High density polarized 3He target. • Run in Hall A from 10/24/08-2/5/09. 110 shift workers, 7 Ph.D. students.
Reaction on a Transversely Polarized 3He TargetE06-010:
JLab, Jan 20101111
CLAS configuration: EG2000CLAS configuration: EG2000
e
Polarizations: Beam: ~70% NH3 proton ~70%
Target position -55cmTorus +/-2250Beam energy ~5.7 GeV
1) Polarized NH3/ND3 ( ~5 days)2) Polarized NH3/ND3 with IC 60 days
Longitudinaly polarized target
ep→e’X
JLab, Jan 201012
Closed (open) symbols reflect data after (before) events from coherent production are subtracted
GRV & CTEQ,@ LO or NLO
E00-108: Leading-Order x-z factorization
Good description for p and d targets for 0.4 < z < 0.65
Hall-C
JLab, Jan 201013
A1 PT-dependence in SIDIS
M.Anselmino et al hep-ph/0608048
+ ALL can be explained in terms of broader kT distributions for f1 compared to g1
02=0.25GeV2
D2=0.2GeV2
In perturbative limit predicted to be constant
(2004)
constituent quark model (Pasquini et al).
0.790.740.74
JLab, Jan 20101414
Quark distributions at large kQuark distributions at large kTT: models: models
Effect of the orbital motion on the q- may be significant (H.A.,S.Brodsky, A.Deur,F.Yuan 2007)
JMR model
q
DqMR , R=s,a
Higher probability to find a quark anti-aligned with proton spin at large kT
u+<u-
JLab, Jan 20101515
Quark distributions at large kQuark distributions at large kTT: lattice: lattice
Higher probability to find a d-quark at large kT
Higher probability to find a quark anti-aligned with proton spin at large kT
B.Musch arXiv:0907.2381
JLab, Jan 201016
Extracting widths from A1
Assuming the widths of f1/g1 x,z and flavor independent
Anselmino et al
Collins et al
Fits to unpolarized data
EMC
JLab, Jan 201017
A1
A1 PT-dependence
CLAS data suggests that width of g1 is less than the width of f1
AnselminoCollins
Lattice
New eg1dvcs data allow multidimensional binning to study kT-dependence for fixed x
JLab, Jan 20101818
kkT T -distributions-distributions in nuclei in nuclei
Higher probability to find a hadron at large PT in nuclei
kT-distributions may be wider in nuclei?
PT = p┴ +z kT CLAS
Hall-C
bigger effect at large z
JLab, Jan 20101919
~10% of E05-113 data
19
Longitudinal Target SSA measurements at CLAS Longitudinal Target SSA measurements at CLAS
p1sin+p2sin2
0.12<x<0.48
Q2>1.1 GeV2
PT<1 GeV
ep→e’X
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 sin2 for +
JLab, Jan 20102020
Kotzinian-Mulders asymmetryKotzinian-Mulders asymmetry
•Measurement of SSAs for pions, provides access to the RSMT TMD (Ralston-Soper (1979), Mulders-Tangerman (1995) •Study Collins fragmentation with longitudinally polarized target
Transversely polarized quarks in the longitudinally polarized nucleon
curves, QSM from Efremov et al
CLAS 2009 (projected)
Wormgear
JLab, Jan 20102121
What we know about What we know about ??
Boffi et al, Phys. Rev. D 78 (2008) 034025
JLab, Jan 201022
Intrinsic transverse momentum densities of the nucleon
genuine effectof intrinsic transversemomentum of quarks
genuine effectof intrinsic transversemomentum of quarks
GPDs
up down
PhH, B. Musch et al.arXiv:0908.1283
PhH, B. Musch et al.arXiv:0908.1283
Ph. Haegler et alarXiv:0908.1283
JLab, Jan 201023
Trento, Nov 1223
Pros1. Small field (∫Bdl~0.005-0.05Tm)2. Small dilution (fraction of events from polarized material)3. Less radiation length4. 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 (use minitorus)
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
HD-Ice target vs std nuclear targets
JLab, Jan 20102424
Collins SSAsCollins SSAs
CLAS with a transversely polarized target will allow measurements of transverse spin distributions and constrain Collins fragmentation function
Anselmino et al (2007) Boffi et al (2009)
helicity-transversity=pretzelosity
CLAS E08-015
JLab, Jan 201025
Electroproduction kinematics: JLab12→EIC
JLab 0.1<xB<0.7 JLab@12GeV
Study of high x domain requires high luminosity, low x higher energies
EIC
JLab12
Q2
EIC
collider experiments
H1, ZEUS 10-4<xB<0.02
EIC 10-4<xB<0.3gluons (and quarks)
fixed target experiments
COMPASS 0.006<xB<0.3
HERMES 0.02<xB<0.3
gluons/valence and sea quarks
valence quarks
JLab, Jan 201026
CLAS12LTCC
FTOF
PCAL
ECHTCC
Lumi = 1035cm-2s-1
High beam polarization 80%High target polarization 85%NH3 (30 days) ND3 (50 days)
Wide detector and physics acceptance (current/target fragmentation)
Replace 2 sectors of LTCC with a proximity RICH detector to identify Kaons approved by JLab PAC34
JLab, Jan 201027
Hall-A: Experimental Setup and parameters
Beam: 50 A, E=8.8 and 11 GeV (80% long. Pol.)Target: 65% polarized 3He GEn(2)/PR-09-016 Luminosity: 1.4×1037 cm-2s-1 , 0.05 sr
BB: e-arm at 30o
= 45 msrGEM TrackerGas CherenkovShower GMn/PR-09-019
SBS:h-arm at 14o
= 50 msrGEM trackerexcellent PID / RICHHadron CALO
e+3He→e’+(K)+X
Event rate: ~104×HERMES60 days of production expected stat. accuracy:
1/10 of proton HERMES
JLab/HallAG. Cates, E. Cisbani, G.B. Franklin, B. Wojtsekhowski
JLab, Jan 201028
Objectives: Extract charge symmetry violating valence PDFs (δd – δu) as function of x
for different Q2 bins.
Where and
RMeasD (x,z)
4RY (x,z) 1
1 RY (x,z)
Experiment: Measure Charged pion electroproduction in semi inclusive DIS off deuterium
E09-002: Executive Summary
RY (x,z) Y D
(x,z)
Y D
(x,z)Conditions: 11 GeV electron beam 10 cm long Liquid deuterium target Hall C SHMS for electron detection Hall C HMS for charged pion detection 17 days of beam time
d d p un
u up dn
28
SHMS
HMS
Hafidi,Gaskell,Dutta
JLab, Jan 201029
Flavor decomposition using CLAS12
10% systematics on asymmetries
E12-09-007 K.Hafidi et al
JLab, Jan 201030
Transverse Momentum Dependence of Semi-Inclusive Pion Production PR12-09-017
(Mkrtchyan,Bosted,Ent)
PR12-09-017: Map the pT dependence (pT ~ < 0.5 GeV) of + and - production off proton and deuteron targets to measure the kT dependence of up and down quarks
Significant net orbital angular momentum of valence quarks implies significant transverse momentum of quarks
Can only be done using spectrometer setup capable of %-
type measurements (an essential ingredient of the global SIDIS program!)
Beam time request: 32 days of beam time in Hall CBeam time request: 32 days of beam time in Hall CSpin-off: Radiative correction modeling for (e,e’)
Single-spin asymmetries at low pT (< 0.2 GeV)
Low-energy (x,z) factorization for kaons
2.9 < Mx2 < 7.8 GeV2
JLab, Jan 20103131
A1 PT-dependence in SIDIS E12-07-107
M.Anselmino et al hep-ph/0608048
•ALL ) sensitive to difference in kT distributions for f1 and g1 •Wide range in PT allows studies of transition from TMD to perturbative approach
02=0.25GeV2
D2=0.2GeV2
Perturbative limit calculations available for :
J.Zhou, F.Yuan, Z Liang: arXiv:0909.2238
JLab, Jan 201032
Boer-Mulders Asymmetry with CLAS12 & EIC
CLAS12 and EIC studies of transition from non-perturbative to perturbative regime will provide complementary info on spin-orbit correlations and test unified theory (Ji et al)
Nonperturbative TMDPerturbative region
Transversely polarized quarks in the unpolarized nucleon
-
CLAS12
EIC
e p5-GeV 50 GeV
sin(C) =cos(2h)
Perturbative limit calculations available for :
J.Zhou, F.Yuan, Z Liang: arXiv:0909.2238
E12-06-112
JLab, Jan 201033
sinLU(UL) ~FLU(UL)~ 1/Q (Twist-3)
1/Q behavior expected (fixed x bin)
Study for Q2 dependence of beam SSA allows to check the higher twist nature and access quark-gluon correlations.
Q2-dependence of beam SSA
Hall-C: E12-06-104R.Ent & H.MkrtchyanStudy R and FL
CLAS: E12-06-112
JLab, Jan 201034
Nonperturbative TMD Perturbative region
sinLU(UL) ~FLU(UL)~ 1/Q (Twist-3)
In the perturbative limit 1/PT behavior expected
Study for SSA transition from non-perturbative to perturbative regime.
EIC will significantly increase the PT range.
PT-dependence of beam SSA E12-06-112
4x60 100 days, L=1033cm-2s-1
JLab, Jan 201035
Study the reaction mechanism in SIDIS
•Check the NLO predictions in the collinear approximation•Provide input to the analysis of other SIDIS experiments in JLab
CLAS12 PR10-010 Puckett et al x=0.4,z=0.5
JLab, Jan 201036
Summary
Measurements of azimuthal dependences of multiplicities as well as double and single spin asymmetries indicate that correlations between spin and transverse motion of quarks may be significant.
PT-dependences of the double and single-spin asymmetries provide important input for studies of flavor and helicity dependence of quark transverse momentum dependent distributions.
JLab SIDIS experiments at 6 GeV will significantly improve the statistical precision of longitudinally polarized target data, and will provide new data on transversely polarized target.
Large kinematical acceptance of CLAS12@ 11 GeV with L=1035cm-2sec-1 combined with high luminosity L=1037cm-2sec-1 precision measurements at Hall-A/C would allow JLab12 to study in details the 3D structure of the nucleon in the valence region.
JLab, Jan 201037
Support slides….
JLab, Jan 201038
Transverse momentum dependence of SIDISGeneral formalism for (e,e’h) coincidence reaction w. polarized beam:
( = azimuthal angle of e’ around the electron beam axis w.r.t. an arbitrary fixed direction)
[A. Bacchetta et al., JHEP 0702 (2007) 093]
LUUTUU
thh
FFx
y
xyQdPdzddxdyd
d,,
22
2
2
2,
{2
1)1(2
}sin)2cos(cos sin)1(2)2cos(cos)1(2 hhhLUheUUhUUh FFF
JLab, Jan 201039
CLAS12: Kinematical coverage
Large Q2 accessible with CLAS12 are important for separation of HT contributions
Q2>1GeV2
W2>4 GeV2(10)y<0.85MX>2GeV
SIDIS kinematics
eX
x=0.3 → Q2=~2 GeV2 (CLAS), ~5 GeV2 (HERMES) ~15 GeV2 (COMPASS)
JLab, Jan 201040
Trento, Nov 1240
Factorization studies
Rpd+ for any z, pt (if d and u have same pt dependence)!
Simple LO picture in valence region:
Rpd- for any z, x!
JLab, Jan 201041
SSA with long. polarized target
quark polarization
JLab, Jan 201042
SSA with long. polarized target
quark polarization
JLab, Jan 201043
SSA with unpolarized target
quark polarization
JLab, Jan 201044
SSA with unpolarized target
quark polarization
JLab, Jan 201045
JLab, Nov 2545
Azimuthal moments with unpolarized target
quark polarization
JLab, Jan 201046
JLab, Nov 2546
Azimuthal moments with unpolarized target
quark polarization
JLab, Jan 201047
JLab, Nov 2547
SSA with unpolarized target
quark polarization
JLab, Jan 201048
JLab, Nov 2548
SSA with unpolarized target
quark polarization
JLab, Jan 201049
More lattice studies
d-quark opposite to ud-quark has wider kT-distribution
JLab, Jan 201050
A1 PT-dependence in SIDIS
M.Anselmino et al hep-ph/0608048
+ A1 suggests broader kT distributions for f1 than for g1
- A1 may require non-Gaussian kT-dependence for different helicities and/or flavors
02=0.25GeV2
D2=0.2GeV2
0.4<z<0.7
JLab, Jan 201051
Dilution factor in SIDIS
Multiple scattering and attenuation in nuclear environment introduces
additional PT-dependence for hadrons
Fraction of events from polarized hydrogen in NH3
Nu,Np -total counts from NH3 and carbon normalized by lumi
u, p -total areal thickness of hydrogen (in NH3), and carbon target
Cn=Nitr/Carbon ratio (~0.98)Diff. symbols for diff x-bins
-
JLab, Jan 20105252
What we know about What we know about ??Boffi EINN2009