H. Avakian, Baryons, Dec 10 1 Transverse spin physics at CLAS and CLAS12 H.Avakian (JLab)...

H. Avakian, Baryons, Dec 101

Transverse spin physics at CLAS and CLAS12

H.Avakian (JLab)H.Avakian (JLab)

BARYONS’10 Dec. 7-11, 2010, Osaka, JapanBARYONS’10 Dec. 7-11, 2010, Osaka, Japan


Outline Outline

•Physics motivation•kT-effects with unpolarized and longitudinally polarized target data•Physics with transversely polarized hadrons and quarks•Future studies of 3D PDFs at CLAS at 6 GeV •Transverse structure & CLAS12

How spin-orbit correlations are related to the orbital momentum, longitudinal structure and nuclear effects?


Structure of the Nucleon

d2k T

Wpu(k,rT) “Mother” distributions (Wigner, GTMDs,..)

d2r T

d2kT

PDFs q(x), q(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), q(x,kT)…

GPD/IPDs H(x,rT), H~(x,rT)…

Nucleon TMDs

Transverse Momentum Distributions (TMDs) of partons describe the distribution of quarks and gluons in a nucleon with respect to x and the intrinsic transverse momentum kT carried by the quarks


SIDIS: partonic cross sections

kT

PT = p┴ +z kT

p┴

Ji,Ma,Yuan Phys.Rev.D71:034005,2005

Use azimuthal moments in SIDIS to study spin-orbit correlations.


CLAS configurationsCLAS configurations

e

ep→e’X

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 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


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

arXiv:1003.4549


Quark distributions at large kQuark distributions at large kTT: lattice: lattice

Higher probability to find a quark anti-aligned with proton spin at large kT and bT

B.Musch et al arXiv:1011.1213

B.Pasquini et al

Significant correlations of spin and transverse degrees of freedom predicted


Quark distributions at large kQuark distributions at large kTT: lattice: lattice

B.Musch et al arXiv:1011.1213

u/u

JMR model

q

DqMR , R=s,a

Sign change of u/u consistent between lattice and diquark model


A1

A1 PT-dependence

CLAS data suggests that width of g1 is less than the width of f1

AnselminoCollins

Lattice

New CLAS data would allow multidimensional binning to study kT-dependence for fixed x

PT

PT

arXiv:1003.4549


~10% of E05-113 data

12

Longitudinal Target SSA measurements at CLASLongitudinal 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 +


Kotzinian-Mulders Asymmetries

B.Musch arXiv:0907.2381B.Pasquini et al, arXiv:0910.1677

HERMES

CLAS (5 days)

Worm gear TMDs are unique (no analog in GPDs)


Beam SSA: ALU from CLAS @ JLab

0.5<z<0.8

Beam SSA from hadronization (Collins effect) by Schweitzer et al.

Photon Sivers Effect Afanasev & Carlson, Metz & Schlegel

Beam SSA from initial distribution (Boer-Mulders TMD) F.Yuan using h1

┴ from MIT bag model

No leading twist contributions: provides access to quark-gluon correlations


x

PT

h

S=y

HT function related to force on the quark. M.Burkardt (2008)

Chiral odd HT-distributionChiral odd HT-distribution

How can we separate the HT contributions?

Compare single hadron and dihadron SSAs

Only 2 terms with common unknown HT G~ term!

M.Radici


1. 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

CLAS transversely polarized HD-Ice targetHD-Ice target vs std nuclear targets


Collins SSAsCollins SSAs

CLAS with a transversely polarized target will allow measurements of transverse spin distributions and constrain Collins fragmentation function

Anselmino et al

CLAS E08-015 (2011)


Measurement of Sivers function and GPD-E

DVCS Transverse asymmetry (function of momentum transfer to proton) is large and has strong sensitivity to GPD-E

CLAS will provide a measurements of Sivers asymmetry at large x, where the effect is large and models unconstrained by previous measurements.

Meissner, Metz & Goeke (2007)

GPD-E=0

(DVCS) (SIDIS) CLAS E08-015


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 allow studies of both current and target fragmentation regions using semi inclusive and exclusive processes

Solenoid 5T

DC R1, R2, R3 LTCC

HTCC

FTOF

PCAL

EC

CLAS12

L = 1035 cm-2s-1

Primary goal of experiments:

study of the 3D structure of the nucleon


CLAS12: Kinematical coverage

Large PT , Q2 accessible with CLAS12 are important for studies of the 3D structure and separation of HT contributions.

Q2>1GeV2

W2>4 GeV2(10)y<0.85MX>2GeV

SIDIS kinematics

eX


E12-06-112:E12-06-112: Pion SIDIS E12-09-008: E12-09-008: Kaon SIDIS

E12-07-107:E12-07-107: Pion SIDIS E12-09-009: E12-09-009: Kaon SIDIS

LOI12-06-108: LOI12-06-108: Pion SIDISLOI12-09-004: LOI12-09-004: Kaon SIDIS

PAC approved experiments & LoI

Nq

U

L

T

Complete program of TMDs studies for pions and kaons

Kaon measurements crucial for a better understanding of the TMDs “kaon puzzle”

Kaon SIDIS program requires an upgrade of the CLAS12

detector PID RICH detector to replace LTCC (talk by P. Rossi)Project under development

TMDs program @ 12 GeV in Hall B


Longitudinally polarized target: helicity distributions

High precision measurements of double spin asymmetries will significantly improve the knowledge of helicity distributions

Wide range in PT of hadrons would allow measurements of transverse momentum dependence of partonic distributions in the valence region


Pretzelosity @ CLAS12:

•CLAS12 will provide pretzelosity measurement in the valence region for Kaons and pions.

B. Pasquini et al. arXiv:0806.2298

Exciting relation:(in bag & spectator model)

g1q (x) h1

q (x)h1Tq (x)

helicity - transversity = ‘measure’ of relativistic effects

In models (bag, diquark) pretzelosity defines the OAM

She, Zhu & Ma, Phys. Rev. D 79 (2009)

http://www.slac.stanford.edu/spires/find/wwwhepau/wwwscan?rawcmd=fin+%22Pasquini,%20B.%22


Nonperturbative TMDPerturbative region

PT-dependence of beam SSA

sinLU(UL) ~FLU(UL)~ 1/Q (Twist-3)

1/PT

Check of the higher twist nature of observed SSA criticalSSA test transition from non-perturbative to perturbative region

1/Q


Summary

•CLAS longitudinally polarized NH3 and ND3 target data provides superior sample of events allowing detailed studies of single and double spin asymmetries using multidimensional bins

Measurements of spin and azimuthal asymmetries with unpolarized, longitudinally polarized and transversely polarized targets in semi-inclusive processes at JLab :

•Measure TMDs of partons in the valence region•Provide detailed info on partonic spin-orbit correlations •Study quark-gluon correlations (HT)•Study nuclear modification of 3D PDFs

CLAS12 will significantly increase the luminosity, kinematical coverage and particle identification capabilities of CLAS6


Support slides….


Some analysis topics for latest polarized proton and deuteron target data

SIDIS with JLab at 6 GeVSIDIS with JLab at 6 GeV

•Inclusive g1p •Inclusive g1d•DVCS AUL on proton•DVCS AULon neutron•DVCS ALL

•SIDIS AUL & ALL for pions on proton•SIDIS AUL & ALL for pions on deuteron•SIDIS AUL & ALL for kaons and on proton

•Modifications of azimuthal moments in nuclei

Large acceptance of CLAS allows simultaneous measurements of hard exclusive and semi-inclusive reactions providing complementary information on the complex nucleon structure.

M.Osipenko

28H. Avakian, Baryons, Dec 10


Some questions to address

• What is the shape of kT-distributions?• Are there correlations between transverse space and momentum

distributions?• Can kT-distributions be flavor dependent?• Are kT-distributions the same for different spin orientations?• How spin-orbit correlations change the momentum distributions?• What is the fraction of kT-generated in FSI?• How quark-gluon correlations affect transverse momentum and space

distributions?• How nuclear medium changes kT and bT-distributions?• How gluons and sea are distributed in kT


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

Nucleon TMDs

Transverse Momentum Distributions (TMDs) of partons describe the distribution of quarks and gluons in a nucleon with respect to x and the intrinsic transverse momentum kT carried by the quarks


HDice

• polarized targets of solid hydrogen, +HD (E06-101); e+HD (E08-021)• polarize to frozen-spin state at 12 mK, 15 tesla in new HDice Lab• transfer to CLAS In-Beam-Cryostat

• renovated Lab in Test Lab Annex• installing polarizing equip• assembling Oxford dilution fridge - training SC magnet• new NMR electronics under test - optimize H D spin transfer• fabricating CLAS target cells• HD purity analysis prep time - chromatography & Raman scat

HDice

• polarized targets of solid hydrogen, +HD (E06-101); e+HD (E08-021)• polarize to frozen-spin state at 12 mK, 15 tesla in new HDice Lab• transfer to CLAS In-Beam-Cryostat

• renovated Lab in Test Lab Annex• installing polarizing equip• assembling Oxford dilution fridge - training SC magnet• new NMR electronics under test - optimize H D spin transfer• fabricating CLAS target cells• HD purity analysis prep time - chromatography & Raman scat

HDiceLab

HDiceLab

HallB

HallB

333333

Single hadron production in hard scattering

Measurements in different kinematical regions for nucleon and nucleus provide complementary information on the complex nucleon structure.

xF - momentum

in the CM frame

xF>0 (current fragmentation)

xF<0 (target fragmentation)

h

h

Target fragmentation Current fragmentation

Fracture Functions

xF

M

0-1 1

h

h

TMD GPD

kT-dependent PDFs Generalized PDFs

PDF

hFF

DA DA

exclusivesemi-inclusive semi-exclusive


Collins fragmentation & higher twists

sT(q×PT)↔ H1┴

y

x

S h

PTS = +h

x

PT

h

S=

y

HT function related to force on the quark. M.Burkardt (2008)

C=hS’D(z,PT)=D1(z,PT)+H1┴(z,PT) sin(C)

Interactions make difference


HDice In-Beam Cryostat for CLAS

HDiceTransferCryostat

• designed for both (Start Counter) and e- (mini-Torus)

• ASME code review nearly complete

• under construction

0.05 K0.6 K

1 K4 K

HDice IBC-CLAS loading

HDice In-Beam Cryostat


coscos moment in A moment in ALLLL-P-PTT-dependence-dependence

PT-dependence of cos moment of double spin asymmetry is most sensitive to kT-distributions of quarks with spin orientations along and opposite to the proton spin.

hep-ph/0608048

02=0.25GeV2

D2=0.2GeV2

CLAS PRELIMINARY


Exclusive and from CLAS

e p e p e pe p π+ π-

e- p e- n+π+π0

+

•Measurements of ratios , … Ju,Jd

Gluon exchange at low W suppressed (x-sections for and comparable)Quark exchange, which dominates, can be considered as part of SIDIS

H. Avakian, Baryons, Dec 10 1 Transverse spin physics at CLAS and CLAS12 H.Avakian (JLab)...

Documents

Transcript of H. Avakian, Baryons, Dec 10 1 Transverse spin physics at CLAS and CLAS12 H.Avakian (JLab)...