Transversity with Solenoid

Haiyan GaoDuke University/TUNL

Dec 14, 2006

J.P. Chen, E. Cisbani, E. Chudakov, X. Jiang,J.C. Peng, X. Qian, L.Y. Zhu

Outline

• Brief Introduction and existing data• Proposed 6-GeV measurements• Preliminary study with Solenoid and

projections• Summary

• It takes two Chiral-odd objects to measure transversity– Drell-Yan (Doubly

transversely polarized p-p collision)

– Semi-inclusive DISChiral-odd distributions

function (transversity)Chiral-odd fragmentation

function (Collins function)

Chiral-quark soliton model

-

The kinematics and coordinate• E’ is the energy of

scattered electron• θe is the scattering

angle• ν=E-E’ is the energy

transfer.• k : quark transverse

momentum

DIS: Q2 and ν is large, but x is finite.

All Eight Quark Distributions Are Probed in Semi-Inclusive DIS

×= 4

26 4

Qsxd πασ

),()(])1(1{[ 211

,

22⊥∑−+ h

qq

qqq PzDxfey

),()()sin()1(||

),()()2sin(4

)1(||

),()()2cos(4

)1(

2

,11

2

2

,1

)1(1

22

2

2

,1

)1(1

22

2

⊥⊥⊥

⊥⊥⊥⊥

⊥⊥⊥⊥

∑

∑

∑

+−+

−−

−+

hqq

qqq

lS

lh

h

hT

hqq

qqLq

lh

hN

hL

hqq

qqq

lh

hN

h

PzHxhezMP

yS

PzHxheMMz

PyS

PzHxheMMz

Py

φφ

φ

φ

)},()()cos()211(||

),()()211(||

),()()3sin(6

)1(||

),()()sin()211(||

21

)1(1

,

2

21

,1

2

,

21

)2(1

223

3

21

)1(1

,

22

⊥⊥

⊥

⊥⊥⊥⊥

⊥⊥⊥

∑

∑

∑

∑

−−+

−+

−−+

−+−+

hqq

Tqq

qlS

lh

N

hTe

hq

qq

qqLe

qqh

qqTq

lS

lh

hN

hT

hqq

Tqq

qlS

lh

N

hT

PzDxgezMPyyS

PzDxgeyyS

PzHxheMMz

PyS

PzDxfezMPyyS

φφλ

λ

φφ

φφ

=f1

h1 =

h1L =

=h1T

f1T =

h1T =

=g1L

g1T =

Unpolarized

Polarized target

Polarziedbeam and

target

SL and ST: Target Polarizations; λe: Beam Polarization

Sivers

Transversity

1, ,

1 1

1

Product of ( ) ( ) is non-zero

A surprising flavor dependence : / 1 Extraction of ( ) requires an independent measurement of

Collins function ( )

unfavored favored

q x H z

H Hq xH z

δ

δ

⊥

⊥ ⊥

⊥

•

• ≈ −•

AUTsin(φ) from transv. pol. H target

Simultaneous fit to sin(φ + φs) and sin(φ - φs)

„Collins“moments

-0.02

0

0.02

0.04

0.06

0.08

0.1

2 ⟨s

in(φ

+φS)

⟩π UT

π+

-0.12

-0.1

-0.08

-0.06

-0.04

-0.02

0

0.02

0.1 0.2 0.3

2 ⟨s

in(φ

+φS)

⟩π UT

π-

x0.2 0.3 0.4 0.5 0.6

6.6% scale uncertainty

z0.2 0.4 0.6 0.8 1

Ph⊥ [GeV]

IIIIIIHERMES PRELIMINARY 2002-2004virtual photon asymmetry amplitudesnot corrected for acceptance and smearing

hep-ex/0507013

(BELLE)

Extraction of Collins functions from the Collins asymmetry measurements

Fits to the Hermes data “Prediction” of the Compass data

, ,1 1 1 1Assuming ( ) (1 ) ( ); ( ) (1 ) (

0.29 0.04, 0.33 0.

)

04

fav fav u

fav unfa

nfav favfav unfav

v

H z C z z D z H z C z z D

C C

z⊥ ⊥= − = −

= − ± = ±( Vogelsang and Yuan, hep-ph/0507266 )

0

0.05

0.1 +πNCollins A

0 0.1 0.2 0.3 0.4-0.15

-0.1

-0.05

-0

0.05

Bx

-π

HERMES PRELIMINARY(not corrected for acceptance and smearing)

0.2 0.3 0.4 0.5 0.6 0.7hz

-0.1

0

0.1

0.2NCollins A

Positive hadrons (COMPASS)

-210 -110

-0.1

0

0.1

0.2

x

Negative hadrons

0.2 0.4 0.6 0.8 1hz

( , )p e e π↑ ′ ( , )d hμ μ↑ ′

, ,1 1/ 1unfavored favoredH H⊥ ⊥ ≈ −

Sivers moments from transversity experiments

“Sivers“ moments

AUTsin(φ-φs) from Hermes transv. pol. H target

First measurement of Sivers asymmetry

Sivers function nonzero → orbital angular momentum of quarks

0

0.02

0.04

0.06

0.08

0.1

0.12

2 ⟨s

in(φ

-φS)⟩π U

T

π+

-0.06

-0.04

-0.02

0

0.02

0.04

0.06

0.1 0.2 0.3

2 ⟨s

in(φ

-φS)⟩π U

T

π-

x0.2 0.3 0.4 0.5 0.6

6.6% scale uncertainty

z0.2 0.4 0.6 0.8 1

Ph⊥ [GeV]

IIIIIIHERMES PRELIMINARY 2002-2004not corrected for acceptance and smearing

hep-ex/0507013

Extraction of Sivers functions from the Sivers moment measurements

Fits to the Hermes data “Prediction” of the Compass data

, ,1 1Assuming ( ) (1 ) ( ); ( ) (1 ) ( )

0.81 0.07, 1.86 0.28

u dT u T d

u dSf x S x x u x f x S x x u x

S

⊥ ⊥

= − ± = ±= − = −

( Vogelsang and Yuan, hep-ph/0507266 )

0

0.05

0.1

0.15

0.2+πNSivers A

0 0.1 0.2 0.3 0.4

-0.05

0

0.05

Bx

-π

HERMES PRELIMINARY(not corrected for acceptance and smearing)

0.2 0.3 0.4 0.5 0.6 0.7hz

-0.3

-0.2

-0.1

-0

0.1 NSivers A

Positive hadrons (COMPASS)

-210 -110

-0.3

-0.2

-0.1

-0

0.1

Bx

Negative hadrons

0.2 0.4 0.6 0.8 1z

Striking flavor dependence of the Sivers function

Hep-ex/0610068: The COMPASS Collaboration

COMPASS leading hadron results

COMPASS all hadron results

Transversity Experiments at Hall A

E-06-010 (update of E-03-004) + E-06-011Single Target-Spin Asymmetry in Semi-Inclusive n↑(e,e′π+/-

) Reaction on a Transversely Polarized 3He Target

Spokespersons:Xiaodong Jiang (Rutgers, Contact Person)

Jian-ping Chen (JLab), Evaristo Cisbani (INFN-Rome)Haiyan Gao (Duke),Jen-Chieh Peng (UIUC)

Approved with A rating, combined beam time of 29 days

Floor Plan

Transversely polarzied 3He target

l

l

z

x

y

hP

Ph

ST

φ S

φ h

l’

scattering plane

hadron plane

l

�� � � � � � � ��

Main Holding Helmholtz Coil

Main Holding Helmholtz Coil

Pick−Up Coils

beame−

oven

RF Drive Coil

2nd

Mai

n H

elm

holtz

Coi

l

2nd

Mai

n H

elm

holtz

Coi

l

Main Holding Helmholtz Coil

RF Drive Coil 2nd MainHelmholtz Coil

beame−

oven

Lasers

Pick−Up Coils

opticsLaser

Lasers (795nm)30W Diode

Three (four)

Target polarization orientation can be rotated to increase the

coverage in ФSl

Vertical Coil Design

The errors with approved beam time will be 33% higher.

Predictions of Collins asymmetry on neutron

The errors with approved beam time will be 33% higher.

Predictions of Sivers asymmetry on neutron

3He target

Solenoid detector for SIDIS

GEMs

Gas Cerenkov

Calorimeter

GEMs

Simulation• Geant3 simulation: COMGEANT

– From Eugene Chudakov.• Event generator (SIDIS):

– Modified from cross-section calculation code (Xiaodong Jiang, Lingyan Zhu and Xin Qian)

• Using CTEQ6.• Using AKK fragmentation function parameterization.

• Detector Geometry:– Assume 17 degrees as the maximum angle– 14.3 degree (newest number)

• 40 cm transversely polarized 3He target. (45% polarization with spin flip technique)

Phase space I

• After DIS selection:– W>2.3 GeV– W’>1.6 GeV– Q2 > 1.0 GeV2

– 0.3<z<0.7

Phase space II

• Full coverage of azimuthal angle.

• Large PTcoverage.

Projections

• 3-dimention: – Bin in x, z and PT.

• 60 days running• Negative charged particle can be collected

at the same time.• With a new kaon PID detector, can provide

nice kaon data.

Projections for Collins and Sivers Asymmetry (π+)

F. Yuan, private communication

Projections for Collins and Sivers Asymmetry (π-)

F. Yuan, private communication

3-D Projections for Collins and SiversAsymmetry (π+)

F. Yuan, private communication Anselmino’s talk

3-D Projections for Collins and SiversAsymmetry (π-)

F. Yuan, private communication Anselmino’s talk

3-D Projections for Collins and SiversAsymmetry (K+)

Anselmino’s talk

3-D Projections for Collins and SiversAsymmetry (Κ-)

Anselmino’s talk

14.3 degree

Summary• The study of kT-dependent quark distribution (transversity,

Sivers function …) and fragmentation functions (Collins function …) is an exciting frontier in nuclear physics. Surprising flavor dependence has been observed in Collins and Sivers function.

• The 6 GeV transversity experiments with polarized 3He target is underway in Hall A to measure the pion SIDIS target single-spin asymmetry on ``neutron’’ (kaon data as the by-product).

• 11 GeV prospect for transversity with Solenoid is extremely bright. These experiments will contribute greatly to the worldwide effort on the study of the transversity.