J.P. Chen, E. Chudakov, X. Jiang, J.C. Peng, X. Qian, L.Y. Zhu · 2006-12-22 · Jian-ping Chen (JLab), Evaristo Cisbani (INFN-Rome) Haiyan Gao (Duke),Jen-Chieh Peng (UIUC) Approved
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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
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
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
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
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
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)
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.
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.
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