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FengFengFengFeng Wei, Wei, Wei, Wei, for the PHENIX for the PHENIX for the PHENIX for the PHENIX CollaborationCollaborationCollaborationCollaboration
New Mexico State University New Mexico State University New Mexico State University New Mexico State University
Transverse Spin Results from
PHENIX at RHIC
6/17/2014 1
2014 RHIC/AGS Annual
Users Meeting
� Introduction
� PHENIX measurements and results
� Opportunities with new detectors
Single Transverse Spin Asymmetries
6/17/2014 2
Xpp +→↑ π
π-
π0
RL
RLN P
Aσσσσ
+−= 1
GeV 20=s
Experiment:(E704, Fermi National Laboratory, 1991)
E704: Left-right asymmetries AN for pions:
Theory Expectation (twist-2):Small asymmetries at high energies
(Kane, Pumplin, Repko, PRL 41, 1689–1692 (1978) )
s
mA q
N∝
Right
Left
AN ~O(10%) Measured
AN ~O(0.1%) Theory
π+
AN
xF
s
px L
F
2=
2014 RHIC/AGS Annual
Users Meeting
2014 RHIC/AGS Annual
Users Meeting
3
How can we understand them?
PRD65, 092008 (2002)
PRL36, 929 (1976)
ZGS
AGS
FNAL
PLB261, 201 (1991)
PLB264, 462 (1991)
RHIC
Non-Perturbative cross section Perturbative cross section
PRL (2004)
Large Transverse Single Spin Asymmetry
(SSA) in forward hadron production
persists up to RHIC energy.
6/17/2014
s = 20GeV
s = 200GeV
s = 7GeV
s = 5GeV
Possible Origin of Large SSAs
6/17/2014 4
( )),(
)(ˆ)(),( ,
21
3
2,121
3
. Thqlkji
Tqi pzFFdxdx
qqqqdxGkxq
dzdxdx
Xppdlk
×→
×⋅∝→ ↑↑
+↑↑ σπσ
fragmentationfunction
pQCDProton Structure
small spindependence
Can initial and/or final state Can initial and/or final state Can initial and/or final state Can initial and/or final state
effects generate large effects generate large effects generate large effects generate large
transverse spin asymmetries? transverse spin asymmetries? transverse spin asymmetries? transverse spin asymmetries?
(A(A(A(ANNNN
~10~10~10~10----1111
))))
h
X’
q
ffffbbbb
ffffaaaa
σ
FFFFFFFFqqqq
2014 RHIC/AGS Annual
Users Meeting
Mechanisms in QCD
DIS 2011 - 6/17/2014 5
... 111 +⊗+⊗∝+−= ⊥⊥
↓↑
↓↑
HδqDfA TN σσσσ
TMD TMD TMD TMD mechanism: mechanism: mechanism: mechanism: GPM includes intrinsic GPM includes intrinsic GPM includes intrinsic GPM includes intrinsic transverse momentumtransverse momentumtransverse momentumtransverse momentum
Possible
Expansion:
Sivers Effect Collins Effect
Sivers Function
(angular momentum)
Transversity
(structure)
Collins Function
(Fragmentation)
TwistTwistTwistTwist----3 Collinear factorization3 Collinear factorization3 Collinear factorization3 Collinear factorization mechanism:mechanism:mechanism:mechanism:
σAt high transverse momenta : various At high transverse momenta : various At high transverse momenta : various At high transverse momenta : various
twisttwisttwisttwist----3 correlation functions, quark3 correlation functions, quark3 correlation functions, quark3 correlation functions, quark----
gluon and gluongluon and gluongluon and gluongluon and gluon----gluon correlation gluon correlation gluon correlation gluon correlation
functions for both initiate state and functions for both initiate state and functions for both initiate state and functions for both initiate state and
final states effects.final states effects.final states effects.final states effects.
2014 RHIC/AGS Annual
Users Meeting
RHIC as Polarized Proton Collider
6/17/2014 6
BRAHMS & PP2PP (p)
STAR (p)
PHENIX (p)
AGS
LINACBOOSTER
Pol. Proton Source500 µA, 300 µs
%P
s
70 upto
GeV 500 upto
Spin Rotators
Partial Siberian Snake
Siberian Snakes
200 MeV Polarimeter AGS Internal PolarimeterRf Dipoles
RHIC pC PolarimetersAbsolute Polarimeter
(H jet)
2 × 1011 Pol. Protons / Bunchε = 20 π mm mrad
2014 RHIC/AGS Annual
Users Meeting
PHENIX Detectors
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2014 RHIC/AGS Annual
Users Meeting
� Central Arm |ηηηη|<0.35, ∆φ=2 X π/2� Drift Chamber (DC)Drift Chamber (DC)Drift Chamber (DC)Drift Chamber (DC)
� PbGlPbGlPbGlPbGl and and and and PbScPbScPbScPbSc ((((EMCalEMCalEMCalEMCal))))
� Ring Imaging Cherenkov Ring Imaging Cherenkov Ring Imaging Cherenkov Ring Imaging Cherenkov Detector(RICHDetector(RICHDetector(RICHDetector(RICH))))
� Pad Chambers (PC)Pad Chambers (PC)Pad Chambers (PC)Pad Chambers (PC)
� Time Expansion Chamber (TECTime Expansion Chamber (TECTime Expansion Chamber (TECTime Expansion Chamber (TEC))))
� Silicon Vertex Detector (VTX)Silicon Vertex Detector (VTX)Silicon Vertex Detector (VTX)Silicon Vertex Detector (VTX)
� Muon Arms 1.2<|η|<2.4, ∆φ=2π� MuonMuonMuonMuon tracker (tracker (tracker (tracker (MuTrMuTrMuTrMuTr))))
� MuonMuonMuonMuon Identifier (Identifier (Identifier (Identifier (MuIDMuIDMuIDMuID))))
� RPC (Trig)RPC (Trig)RPC (Trig)RPC (Trig)
� Forward VTX (FVTX)Forward VTX (FVTX)Forward VTX (FVTX)Forward VTX (FVTX)
� Muon Piston Cal. (MPC) 3.1<|η|< 3.9 � Photons� MPX-EX upgrade (2015)
� Global Detectors (Lumi, Trigger, local Pol.)� BBC � ZDC (neutron)
Integrated Luminosity and Polarization
6/17/2014 8
Year of RHIC Run
Energy [GeV]
Polarization [%]
Recorded L [pb-1]
FOM (P2L)[nb-1]
2002 200 15 0.15 3.4
2005 200 47 0.16 35
2006 62.4 48 0.02 4.6
2006 200 50 2.7 700
2008 200 45 5.2 1100
2012 200 60 9.2 3300
2014 RHIC/AGS Annual
Users Meeting
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PHENIX Measurements PHENIX Measurements PHENIX Measurements PHENIX Measurements
and Resultsand Resultsand Resultsand Results
The Gluon distribution measurement
6/17/2014
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Heavy Heavy Heavy Heavy flavor production flavor production flavor production flavor production
dominated by dominated by dominated by dominated by gluongluongluongluon----gluon gluon gluon gluon
fusion at RHIC fusion at RHIC fusion at RHIC fusion at RHIC energyenergyenergyenergy
�Heavy Flavor (especially D meson) production is an idea tool to investigate gluon distribution.
�SSA in heavy flavor production revealed the tri-gluon correlations by using the twist-3 collinear factorization framework.� Z. Kang, J. Qiu, W. Vogelsang,
F. Yuan, PRD78:114013 (2008)� Y. Koike, S. Yoshida
PRD84:014026 (2011)
Measurement of Heavy flavor decay muon
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MuonMuonMuonMuon Spectrometer:Spectrometer:Spectrometer:Spectrometer:
�1.2<|η|<2.4
�Azimuthal: ΔΦ=2πInclusive Inclusive Inclusive Inclusive MuonsMuonsMuonsMuons
�Heavy Flavor
decay muons
�Stopped
hadrons
�Punch-through
hadrons
�Hadron decay
muons
������
=���� − ∙ ��
��
1 − =
���
���
Distinguished Distinguished Distinguished Distinguished
backgroundbackgroundbackgroundbackground
NonNonNonNon----distinguished distinguished distinguished distinguished
backgroundbackgroundbackgroundbackground
AN
of heavy flavor decay muon
6/17/2014
2014 RHIC/AGS Annual
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�New installed FVTX New installed FVTX New installed FVTX New installed FVTX
detector will be expected detector will be expected detector will be expected detector will be expected
to provide better to provide better to provide better to provide better
rejection on hadron rejection on hadron rejection on hadron rejection on hadron
background in 2015 background in 2015 background in 2015 background in 2015
transverse runtransverse runtransverse runtransverse run
�Currently Measured ACurrently Measured ACurrently Measured ACurrently Measured ANNNN
are are are are
consistent with zero.consistent with zero.consistent with zero.consistent with zero.
�2012 data analysis is very 2012 data analysis is very 2012 data analysis is very 2012 data analysis is very
close to be finalized, close to be finalized, close to be finalized, close to be finalized,
which significantly which significantly which significantly which significantly
constraints the statistical constraints the statistical constraints the statistical constraints the statistical
uncertainty in highest puncertainty in highest puncertainty in highest puncertainty in highest pTTTT
bin within ~10%.bin within ~10%.bin within ~10%.bin within ~10%.
AN
of J/ψ
6/17/2014
2014 RHIC/AGS Annual
Users Meeting
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Test production Test production Test production Test production
mechanismmechanismmechanismmechanism
• Only color singlet Only color singlet Only color singlet Only color singlet
generate SSAgenerate SSAgenerate SSAgenerate SSA
The results are The results are The results are The results are
consistent with consistent with consistent with consistent with
zero.zero.zero.zero.
AN
of Mid-rapidity π0
and η
6/17/2014
2014 RHIC/AGS Annual
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Anselmino et al, PRD
74, 094011 (2006)�The π0 and η production
is sensitive to qg and ggprocess
� Improved a factor of 20 statistical uncertainties on the previous measurement and extend to higher pT� Phys. Rev. Lett. 95,
202001 (2005)� Includes η mesons�Consistent with zero for
both π0 and η PPG135, Submitted to PRD arXiv:1312.1995
Forward AN
for MPC Clusters
6/17/2014 15
Measurements Measurements Measurements Measurements
from MPC from MPC from MPC from MPC
3.1<|3.1<|3.1<|3.1<|ηηηη|<3.9|<3.9|<3.9|<3.9
2014 RHIC/AGS Annual
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PPG135, Submitted to PRD arXiv:1312.1995
Forward AN
as a function of pT
6/17/2014
2014 RHIC/AGS Annual
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� Rises and plateaus at high pT� Consistent with Twist-3 expectation
� Y. Koike etc. Phys.Rev. D85 (2012) 034030
PPG135, Submitted to PRD arXiv:1312.1995
Comparison to BRAHMS for MPC at 62.4GeV
6/17/2014
2014 RHIC/AGS Annual
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Pion FF studied in PYTHIA�u→π+, d→π+ (100/0)�u→π-, d→π- (50/50)�u→π0, d→π0 (25/75)
The Origin of AN not explained by Sivers alone, assuming if� PYTHIA holds� u-d Sivers from SIDIS holds in
p↑+p → π + X
PPG135, Submitted to PRD arXiv:1312.1995
Forward AN
for η mesons
6/17/2014
2014 RHIC/AGS Annual
Users Meeting
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PPG170,
arXiv: 1406.3541
Interference Fragmentation
6/17/2014
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Interference Fragmentation Interference Fragmentation Interference Fragmentation Interference Fragmentation Function (HFunction (HFunction (HFunction (H1111
):):):):
Fragmentation of a transversely polarized quark q into two spin-less
hadron h1, h2 carries an azimuthal dependence
TransversityTransversityTransversityTransversity
IFFIFFIFFIFF
⊗
Mid-Rapidity IFF Measurement
6/17/2014 20
2014 RHIC/AGS Annual
Users Meeting
�PHENIX measurements in
2006 and 2008 have seen
non-zero asymmetries.
�STAR has also seen non-
zero asymmetries
�Move to more forward,
MPC-ex upgrade in 2015
6/17/2014
2014 RHIC/AGS Annual
Users Meeting
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PHENIX Opportunities PHENIX Opportunities PHENIX Opportunities PHENIX Opportunities
with New Detectorswith New Detectorswith New Detectorswith New Detectors
π�µ
Drell-Yan prompt
FVTX installed in 2012
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2014 RHIC/AGS Annual
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4 layers 4 layers 4 layers 4 layers of FVTX endof FVTX endof FVTX endof FVTX end----caps cover caps cover caps cover caps cover
1.2<|1.2<|1.2<|1.2<|ηηηη|<2.4 with resolution |<2.4 with resolution |<2.4 with resolution |<2.4 with resolution ~100um. ~100um. ~100um. ~100um.
� Precise Charm/Beauty, W/Z Measurements� Drell-Yan, J/ψ … via dimuons
Align
Wedges
Residual (μm)
FVTX aligned to <10 µm
Projected Open Charm AN
with FVTX
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2014 RHIC/AGS Annual
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FFFF
xxxx
-0.4-0.4-0.4-0.4 -0.3-0.3-0.3-0.3 -0.2-0.2-0.2-0.2 -0.1-0.1-0.1-0.1 0000 0.10.10.10.1 0.20.20.20.2 0.30.30.30.3 0.40.40.40.4
NN NN
AA AA
-0.2-0.2-0.2-0.2
-0.15-0.15-0.15-0.15
-0.1-0.1-0.1-0.1
-0.05-0.05-0.05-0.05
0000
0.050.050.050.05
0.10.10.10.1
0.150.150.150.15
0.20.20.20.2
0.250.250.250.25
0.30.30.30.3
w ith FV TX w ith FV TX w ith FV TX w ith FV TX
NNNN
C haC haC haC harrrrm Am Am Am A
= 200 G eV = 200 G eV = 200 G eV = 200 G eVssss + X , + X , + X , + X , µ →p + p p + p p + p p + p
|z| < 10c |z| < 10c |z| < 10c |z| < 10cmmmm ,,,, PPPP = 60 = 60 = 60 = 60 % % % %
-1-1-1-1
21 pb21 pb21 pb21 pb
----µP H E N IX (R un6) P H E N IX (R un6) P H E N IX (R un6) P H E N IX (R un6)
| < 1.9 | < 1.9 | < 1.9 | < 1.9 η1.4 < |1.4 < |1.4 < |1.4 < |
< 5 G eV /c < 5 G eV /c < 5 G eV /c < 5 G eV /c
TTTT
1 < p1 < p1 < p1 < p
|, M axim um gluon|, M axim um gluon|, M axim um gluon|, M axim um gluon
NNNN
|A|A|A|A
|, M axim um quark|, M axim um quark|, M axim um quark|, M axim um quark
NNNN
|A|A|A|A
A nselm ino et. al.A nselm ino et. al.A nselm ino et. al.A nselm ino et. al.
P R D 70(2004)074025P R D 70(2004)074025P R D 70(2004)074025P R D 70(2004)074025
= 1.5 G eV /c = 1.5 G eV /c = 1.5 G eV /c = 1.5 G eV /c
TTTT
pppp
SSSS ys. Eys. Eys. Eys. E rrrrrrrr....
2015
μ+
μ-
FVTX
�Significant rejection of Significant rejection of Significant rejection of Significant rejection of
hadron backgroundhadron backgroundhadron backgroundhadron background
�Limited power on D/B Limited power on D/B Limited power on D/B Limited power on D/B
separation separation separation separation
�Transverse spin data expected Transverse spin data expected Transverse spin data expected Transverse spin data expected
from 2015from 2015from 2015from 2015
Drell-Yan Process
6/17/2014 24
SIDIS2
1Yan-Drell2
1 |),(|),( TTTT kxfkxfrr
⊥⊥ ∆−=∆Xlpl ++→+ πXllpp ++→+ −+
SIDISSIDISSIDISSIDISDrellDrellDrellDrell----YanYanYanYan
Time reversedTime reversedTime reversedTime reversed
� No fragmentation (no Collins effect folded)
� TMD factorization is valid
� The Sivers function in DY is opposite to that in DIS
which can test current SSA QCD mechanisms (TMD & Twist-3)
� ATT
in Drell-Yan is sensitive to transversity!
Initial State
interaction
Final State
Interaction
2014 RHIC/AGS Annual
Users Meeting
Drell-Yan Projection
6/17/2014 25
μ
μ
2014 RHIC/AGS Annual
Users Meeting
RHIC 1-year running projection
DOE milestone
HP13
~2015
MPCMPCMPCMPC----EXEXEXEX
A combined charged particle tracker and
EM pre-shower detector – dual gain
readout allows sensitivity to MIPs and full
energy EM showers.
•π0 rejection � direct photons
•π0 reconstruction out to >80GeV
Coming soon: MPC-EX (2015+)
3.1<|η|<3.9
Dir. Photon AN
6/17/2014
2014 RHIC/AGS Annual
Users Meeting
26
Polarized p+A at RHIC(2015+)
�Large transverse spin asymmetry AN
at forward rapidity – a
large analyzing power at large x1
�Gluon saturation/CGC probed at forward rapidity in p+A –
small x2
in A
A new probe A new probe A new probe A new probe –––– using a large spin asymmetry to study CGC effects in the forward rapidityusing a large spin asymmetry to study CGC effects in the forward rapidityusing a large spin asymmetry to study CGC effects in the forward rapidityusing a large spin asymmetry to study CGC effects in the forward rapidity
6/17/2014
2014 RHIC/AGS Annual
Users Meeting
x2
x2
∆σ forward ~ ∆f (x1) ⊗ g(x2); x1 >> x2
x1∼
p⊥
√
s
e
+ y
∼ 1
x2∼
p⊥
√
s
e− y
1
projectile:
target:
valence
gluonx1
pA
x2
A
pA →h
N
A
pp→h
NP
2
h ⊥
Q2
s
≈
Q
2
sp
Q
2
sA
e
P
2
h ⊥
δ2
Q
4
sp
27
-------- p+Si
-------- p+Cu
-------- p+Au
Forward PionForward PionForward PionForward Pion SingleSingleSingleSingle----Spin AsymmetrySpin AsymmetrySpin AsymmetrySpin Asymmetry
Kang, Yuan (2011)
Summary and Outlook
6/17/2014 28
�PHENIX has measured AN in heavy flavor production� Statistics is still limited and 2012 data will be included� Previous AN of J/ψ was published and consistent with 2012 data
�AN of π0 and η at mid- and forward rapidity was measured� Current results prepare to be published� Expected much improved measurements with MPC-ex
�AN from Interference Fragmentation was measured� Expect 2012 result soon with more forward measurement
�Forward measurements with FVTX� Expect significant background projection in heavy flavor production� Drell-Yan measurement becomes possible
�More opportunities with polarized p+A experiments in future
2014 RHIC/AGS Annual
Users Meeting
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2014 RHIC/AGS Annual
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ThanksThanksThanksThanks
6/17/2014
2014 RHIC/AGS Annual
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Back upBack upBack upBack up
Spin in transversely polarized protonSpin in transversely polarized protonSpin in transversely polarized protonSpin in transversely polarized proton
6/17/2014
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31
31
� Quark transversity
� Know much better about quark
transversity than before.
� Gluon transversity
� No transversely polarized
gluon.
� Parton orbital angular
momentum
� The Sivers function could be
related to orbital angular
momentum.
� Quark Quark Quark Quark SiversSiversSiversSivers function is function is function is function is
constrained OK.constrained OK.constrained OK.constrained OK.
� Gluon Gluon Gluon Gluon SiversSiversSiversSivers function is not function is not function is not function is not
well known. well known. well known. well known.
M.AnselminoM.AnselminoM.AnselminoM.Anselmino
et. al.et. al.et. al.et. al.
NuclNuclNuclNucl. Phys. . Phys. . Phys. . Phys.
Proc. Suppl. Proc. Suppl. Proc. Suppl. Proc. Suppl.
191, 98 191, 98 191, 98 191, 98
(2009).(2009).(2009).(2009).
Eur.Phys.JEur.Phys.JEur.Phys.JEur.Phys.J. . . .
A39:89A39:89A39:89A39:89----
100,2009100,2009100,2009100,2009
x pT
Forward AN
Challenge: pT
Dependence
6/17/2014
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Valence Valence Valence Valence Quarks’ Quarks’ Quarks’ Quarks’ SiversSiversSiversSivers----like like like like or Collins effects?or Collins effects?or Collins effects?or Collins effects?
�No sign of 1/pT falloff yet.� Collins?� Twist-3 pT dependent not trivial
�Much improved with MPC-EX (2015+)
Sub-process fractions p+p 200GeV
AN ~1
Q@twist − 3
x1
Y. Koike, 2012
Possible Mechanisms for AN
6/17/2014
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SP
kT,qp
p
SP
p
p
Sq kT,π
Sq
Sivers mechanism: Correlation between nucleon spin and parton kT
Phys Rev D41 (1990) 83; 43 (1991) 261
Collins mechanism: Transversity(quark polarization) * Spin-dependence in the jet fragmentation
Nucl Phys B396 (1993) 161
- Quarks’ Sivers and Collins TSSA observed in SIDIS
- Gluons’ Sivers not constrained in SIDIS @LO
Requires full jet measurements
- forward s/ePHENIX upgrade
Forward focus:
- Valence quark Sivers via pion
- Gluon Sivers via heavy quarks
- Drell-Yan Sivers sign change
Orbital Angular Momentum?Orbital Angular Momentum?Orbital Angular Momentum?Orbital Angular Momentum?
Semi-classical Interpretation
6/17/2014
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� Attractive rescattering of hit quark by gluon creates transverse momentum� M.Burkardt [hep-ph0309269] – impact parameter formalism� Orbital angular momentum at finite impact parameter� Observed and true x differ� Observable left/right asymmetry
P1
P2
1. Nuclear Shadowing
(angular momentum)
2. Impact Parameter
Space Changes with
polarization
Two Possibilities:Two Possibilities:Two Possibilities:Two Possibilities:
Heavy Quark TSSA at RHIC
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2014 RHIC/AGS Annual
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Koike et. al. (2011)
Kang, Qiu, Vogelsang, Yuan (2008)
AN (D) ≠?
AN (D)
g + g → c + c
c → µ+
c → µ−
δ f = +1(c); −1(c )
PHENIX Preliminary Data
Calculation/plot by Koike
PHENIX preliminary data
Plots by Koike
TwistTwistTwistTwist----3 tri3 tri3 tri3 tri----gluon correlation functions gluon correlation functions gluon correlation functions gluon correlation functions
AN
for Di-hadron
6/17/2014 36
ηminηmax
-3.7-3.1
-2.4-1.2
-0.35+0.35
1.22.4
3.13.9
Similar analysis possible in different combinations of rapidity
• Sivers asymmetry(qT┴)
• No asymmetry expected for qT
||
• Improved statistics for 2008 data set!
TMD is not valid for
back to back di-hadron
process in p+p
collision
2014 RHIC/AGS Annual
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Forward AN
for Charged Hadrons
6/17/2014 37
� Measured at Muon Arms
1.2<|η|<2.4
� No PID – Unidentified
charge hadrons
h+/-
2014 RHIC/AGS Annual
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Mechanisms in QCD
6/17/2014 38
... 111 +⊗+⊗∝+−= ⊥⊥
↓↑
↓↑
HδqDfA TN σσσσ
TMD TMD TMD TMD mechanism: mechanism: mechanism: mechanism: GPM includes intrinsic GPM includes intrinsic GPM includes intrinsic GPM includes intrinsic transverse momentumtransverse momentumtransverse momentumtransverse momentum
Possible
Expansion:
Sivers Effect Collins Effect
Sivers Function
(angular momentum)
Transversity
(structure)
Collins Function
(Fragmentation)
TwistTwistTwistTwist----3 Collinear factorization3 Collinear factorization3 Collinear factorization3 Collinear factorization mechanism:mechanism:mechanism:mechanism:
σAt high transverse momenta : two twist-3
correlation functions
1. Quark-gluon correlation function
2. Two independent trigluon correlation
functions
)()( , dG
fG TT
fqT ,
2014 RHIC/AGS Annual
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