May 29, 2008.

Transversity and TMD Measurements at Jefferson Lab Hall A and Hall C

Transversity-2008, Ferrara, Italy.

Xiaodong Jiang, Los Alamos National Laboratory

Status of Hall A polarized 3He SSA@6GeV.

Hall C SIDIS cross section @ 6 GeV.

Pt distributions in SIDIS.

Plans of Hall A and Hall C SIDIS@12GeV.

Measurements of SIDIS cross section ratio at Jlab-12GeV.

Thanks to: JLab E06-010/E06-011, E. Cisbani, J.-P. Chen, H. Gao, J.-C. Peng et al.JLab-E00-108, R. Ent, P. Bosted, H.Makrtchyan, T. Navasardyan et al.and B. Wojtsekhowski, H. Lu.

E06-010/E06-011: Transverse Target SSA Measurement at Jefferson Lab Hall A Using a Polarized

3He Target (Neutron)

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Jefferson Lab Hall A E06-010/E06-011 Collaboration

Institutions

California State Univ., Duke Univ., Florida International. Univ., Univ. Illinois, JLab, Univ. Kentucky, LANL,Univ. Maryland, Univ. Massachusetts, MIT, Old Dominion Univ., Rutgers Univ., Temple Univ., Penn State Univ., Univ. Virginia, College of William & Mary, Univ. Sciences & Tech, China Inst. Of

Atomic Energy, Beijing Univ., Seoul National Univ., Univ. Glasgow, INFN Roma and Univ. Bari, Univ. of Ljubljana, St. Mary’s Univ., Tel Aviv Univ.

A.Afanasev, K. Allada, J. Annand, T. Averett, F. Benmokhtar, W. Bertozzi, F. Butaru, G. Cates, C. Chang, J.-P. Chen (Co-SP), W. Chen, S. Choi, C. Chudakov, E. Cisbani(Co-SP), E. Cusanno, R. De

Leo, A. Deur, C. Dutta, D. Dutta, R. Feuerbach, S. Frullani, L. Gamberg, H. Gao(Co-SP), F. Garibaldi, S. Gilad, R. Gilman, C. Glashausser, J. Gomez, M. Grosse-Perdekamp, D.

Higinbotham, T. Holmstrom, D. Howell, M. Iodice, D. Ireland, J. Jansen, C. de Jager, X. Jiang (Co-SP), Y. Jiang, M. Jones, R. Kaiser, A. Kalyan, A. Kelleher, J. Kellie, J. Kelly, A. Kolarkar, W.

Korsch, K. Kramer, E. Kuchina, G. Kumbartzki, L. Lagamba, J. LeRose, R. Lindgren, K. Livingston, N. Liyanage, H. Lu, B. Ma, M. Magliozzi, N. Makins, P. Markowitz, Y. Mao, S. Marrone, W. Melnitchouk, Z.-E. Meziani, R. Michaels, P. Monaghan, S. Nanda, E. Nappi, A. Nathan, V.

Nelyubin, B. Norum, K. Paschke, J. C. Peng (Co-SP), E. Piasetzky, M. Potokar, D. Protopopescu, X. Qian, Y. Qiang, B. Reitz, R. Ransome, G. Rosner, A. Saha, A. Sarty, B. Sawatzky, E. Schulte, S. Sirca, K. Slifer, P. Solvignon, V. Sulkosky, P. Ulmer, G. Urciuoli, K. Wang, Y. Wang, D. Watts, L. Weinstein, B. Wojtsekhowski, H. Yao, H. Ye, Q. Ye, Y. Ye, J. Yuan, X. Zhan, X. Zheng, S. Zhou.

Collaboration members

SIDIS: N(e,e’h)h=π+/K+ or π-/K-

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Kinematic coverage

E-arm at θ=30°,

0.5 < E’ < 2.2 GeV.

0.13 < x < 0.405, cover thevalence-quark region.

1.3 < Q2 < 3.1 (GeV/c)2.

2.33 < W < 3.05 GeV, above the resonances region.

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Coverage of hadronkinematics

H-arm at θ = 16°, measure charged hadrons with p = 2.4 GeV/c.

The fraction of the energy transfer carried by the hadron, z = Eh/ν, is z ≈ 0.5 , leading hadron in the current fragmentation.

Missing mass W ’ > 1.5 GeV to stay away from the resonance production region.

Pt cover to ~0.5 GeV/c.

Separation of Collins and Sivers effects through angular dependence

Freedom in target spin orientation: separation of Collins and Sivers asymmetries.

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Coverage of the Collins angle90 (re0 (black 270 (pur), pl180 (blue )),d), e

l l

Coll

l

S

l

ins h S

l l

S SS

<x>=0.135

<x>=0.405

<x>=0.225

<x>=0.315

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Coverage of the Sivers angle

90 (red0 (black), 180 (blue), 270 (purpl )), e

l l

Siver

ll

S

l

S

s h S

l

S S

<x>=0.135

<x>=0.405

<x>=0.225

<x>=0.315

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Hall-A polarized 3He target

40-cm long Rb-K spin-exchange hybrid cell at 10 atm with beam current of 15 μA

42% target polarization with spin-flip, driven by RF frequency, every 20 minutes. Target holding field stays the same.

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Projections of Collins asymmetry on neutron

1 1 1 1/ /unfav fav unfav favH H D D

1 1/ 1unfav favH H

(Need to update theory curves from Alex’s talk yesterday).

Recall that:

2 (1)

1 1

2 (1)

1 1

2 2

1 1

2

1 1

( ) ( )(1 )

(1 / 2) (

( ) ( )

(

(

)

)

( )

)

q q

qqCollin

q q

q TqSivers

UT q q

q

s

UT

q

q

q q

q

e h x H zyA

y y e f x D

e f x D zA

e f x z

z

D

At JLab 6GeV kinematics, Collins asymmetry will be small (?)

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Sivers asymmetry on neutron

Consider that Compass proton Sivers~0, will neutron Sivers be large ?

<Q2>=2.2 (GeV/c)2

Is d-quark Siverslarge ?

With an opposite sign to u-quark Sivers ?

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Sivers asymmetry on neutron

<Q2>=2.2 (GeV/c)2

Status of E06-010/E06011

• Installation starts in Hall A on June 9th, 2008.

• A detector test run has been conducted in May 2008.

• Data taking: Oct 9, 2008 – Jan 15, 2009.

• Please update theory predictions on neutron SSA.

• Nuclear effects of 3He->n correction: please see Sergio Scoppetta’s talk.

Can we really access quark information through SIDIS at Jlab-6 GeV (and 12 GeV) ?

Do we understand the fundamental cross sections in terms of parton density and quark Frag. Func. ?

Fragmentation. Quark information carried out by hadron ?

Hard scattering. How do we know that we hit a quark ?

Jlab Hall C experiment E00-108 (R.Ent H.Makrtchyanet al.)

E00-108: SIDIS cross sections E0=5.5 GeV

At x=0.32, Q2=2.30 GeV2, a z-scan 0.3~1.0 (small Pt).

On proton and deuteron target, π+ and π- productions.

At z=0.55, a x-scan 0.2~0.5 (Q2: 2.0~4.0, small Pt).

At x=0.32, Q2=2.30, z=0.55, a Pt scan 0~0.4 GeV/c.

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Data are well described by SIDIS calculations for 0.3 < z < 0.7

Cross Sections: T. Navarsardyan et al., PRL 98 (2007) 022001.

Smooth cross sections for z: 0.3~0.7.

Different reactions follow a similar trend.

Curves take (partonpdf)*(Frag. Func.)

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Ratios of combined cross sections

z-dependency mostly cancel out in combinedratios.

Closed (open) symbols reflect data after (before) events from coherent r production are subtracted

GRV & CTEQ,@ LO or NLO

(recall, z = 0.65 ~Mx

2 = 2.5 GeV2)

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Neglect sea quarks and assume no pt dependence to parton distribution functions

Fragmentation function dependence drops out in Leading Order

[sp(p+) + sp(p

-)]/[sd(p+) + sd(p

-)]

= [4u(x) + d(x)]/[5(u(x) + d(x))]~ sp/sd independent of z and pt

[sp(p+) - sp(p

-)]/[sd(p+) - sd(p

-)]= [4u(x) - d(x)]/[3(u(x) + d(x))]

Angular dependence at low Pt (arXiv:0709.3020)

dσ ≈ exp(-bPt2)[1+Acosφ+Bcos(2φ)]

Average Pt~0.05 GeV/c.

Found no significant

difference for A and B in

π+, π- on proton or deuteron.

A and B close to zero for SIDIS.

A and B are rather large at the exclusive limit (open circles).

Solid line: Cahn(1978).

Dashed line: Levelt-Mulders(1994).

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kT-dependent in SIDIS

pt = Pt – z kt + O(kt2/Q2)

p

m

xTMD

TMDu(x,kT)

f1,g1,f1T ,g1T

h1, h1T ,h1L ,h1

Transverse momentum of the detected pion Pt arises from convolution of the struck quark transverse momentum kt

with the transverse momentum generated during the fragmentation pt.

Linked to framework of Transverse Momentum Dependent Parton Distributions

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Transverse momentum dependence of SIDIS cross section

Pt dependence very similar for proton and deuterium targets, but deuterium slopes systematically smaller?

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A simple model fit to separate Pt dependency of quark distribution and quark frag. func. with many assumptions .

(m+)2 ~ width of D+(z,pt), (m)2 ~ width of D-(z,pt), (mu)2 ~ width of u(x,kt), (md)2 ~ width of d(x,kt)

kt width of d-quark lis arger than u-quark.Pt width of favored F.F. is similar to that of unfavored F.F.

Di-quark model, Jkob, Mulders, Rodrigues (1997)

DIS 2008 25

R = sL/sT for SIDIS

p

quark

“Semi-inclusive DIS”

RSIDIS RDIS disappears with Q2!

“Deep exclusive scattering” is the z 1 limit of this “semi-inclusive DIS” process

Where, R = sL/sT ~ Q2

What R will behave like at large pT?

Jlab-12GeV projected data compare with Cornell data of 70’s. R. Ent et al.

At Jlab-12GeV, the first question to address:

can we access quark information through SIDIS ?

Universality of Frag. Func. agree with e+e-, p+p data ?

Do we understand the fundamental cross sections in SIDIS, to NLO ?

Fragmentation. Quark information carried out by hadron ?

Hard scattering. How do we know that we hit a quark ?

Do we understand their relative relations, Q2, z, pt and φ-dependencies ?

Need to establish the baseline of interpretation.

SIDIS cross sections at NLO

NLO global fits for Fragmentation Functions

Fit compare with HERMES SIDIS data, R. Sassot et al. 2007.

A global fit to e+e-, SIDIS and p+p data.

Predict cross section at NLO for Jlab-12GeV.

We can measure cross sections and their Q2, pt and z-dependence, for example, with the CLAS12 detector.

Curve: Prediction in NLO

from R. Sassot .

Q2=2.5, x=0.2,0.3,0.4,0.5

SU(2) symmetry in the fragmentation process ?

π0=(π+ + π-)/2

Map out z-dependency.

and map out the Q2 dependency (E0=11,8.8 and 6.6 GeV).

Q2-dependence , same Q2 point covered by different beam energy.

Q2 dependency in many kinematic bins

Curve: Prediction in NLO

from R. Sassot.

z=0.5, x=0.2,0.3,0.4,0.5

and form the combined-ratios of cross sectionsAt LO no z-dependency.

Even at NLO, z-dependency mostly disappeared.

ratios become completely determined by quark distributions.

A clear evidence to prove that quark information is well-preserved in the fragmentation process.

At 5.5 GeV, we already know from Hall C data…

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Closed (open) symbols reflect data after (before) events from coherent r production are subtracted

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JLab-12GeV Hall A: Multi Purpose Spectrometer

- Magnet: 46 cm gap, 2-3 Tesla*m- Solid angle is 70 msr at 15 deg.- GEM chambers with 70 mm resolution- momentum resolution is 0.5% for 5 GeV/c- angular resolution is 0.3 mr- PID detector for π/K separation (RICH).

GEMs

Physics experiments with MPS

Exclusive processes

Polarized and exotic targets

Nucleon FFs (GEP,GMP,GMN)DVCS, WACSSingle pion productionPhi meson productionJ/Psi photo-productione,e’pand e,e’ at large Q2 & low W

GEN with He-3Pol. DISPol. SIDIST/He-3 for u/dALL-WACS

Neutron Transversity with MPS in Hall A

In one month 30,000 times more events than in all transv. data collected by HERMES

Single run of MPS will provide full coverage

for all P > 1/6 of P||

Phase space coverage: Hall A E0=11 GeV

h-arm: MPS at 14 degree.e-arm: BigBite at 30 degree with 1.5-4.5 GeV/c acceptance (E. Cisbani).

Angular coverage (one spin direction)

Rotate target spin to cover Collins and Sivers angle.

Large phase space coverage in (Pt, Q2, z).

100X solid angle than the 6GeV experiment.

Possibility of multi-demensional measurement within a reasonable time.

Kaon asymmetry (with HERMES RICH detector).

May 29, 2008.

Summary

Transversity-2008, Ferrara, Italy.

Hall A polarized 3He SSA@6GeV starts in Oct. 2008.

SIDIS cross section at 6 GeV reasonably well understood.

φ and Pt distributions measured in Hall C.

Many opportunities for Hall A and Hall C SIDIS measurements at Jlab-12GeV.

Measurements of SIDIS cross section ratio at Jlab-12GeV.

Thanks to: E. Cisbani, J.-P. Chen, H. Gao, J.-C. PengR. Ent, P. Bosted, H.Makrtchyan, T. Navasardyanand B. Wojtsekhowski, H. Lu.