transverse spin results from phenix at rhic · pdf filetransverse spin results from phenix at...

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=


Users Meeting


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


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.


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


Users Meeting

PHENIX Detectors

6/17/2014 7


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


Users Meeting

6/17/2014


Users Meeting

9

PHENIX Measurements PHENIX Measurements PHENIX Measurements PHENIX Measurements

and Resultsand Resultsand Resultsand Results

The Gluon distribution measurement

6/17/2014


Users Meeting

10

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

6/17/2014


Users Meeting

11

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


Users Meeting

12

�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


Users Meeting

13

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


Users Meeting

14

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


Users Meeting

PPG135, Submitted to PRD arXiv:1312.1995

Forward AN

as a function of pT

6/17/2014


Users Meeting

16

� Rises and plateaus at high pT� Consistent with Twist-3 expectation

� Y. Koike etc. Phys.Rev. D85 (2012) 034030


Comparison to BRAHMS for MPC at 62.4GeV

6/17/2014


Users Meeting

17

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


Forward AN

for η mesons

6/17/2014


Users Meeting

18

PPG170,

arXiv: 1406.3541

Interference Fragmentation

6/17/2014


Users Meeting

19

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


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


Users Meeting

21

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

6/17/2014


Users Meeting

22

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

6/17/2014


Users Meeting

23

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


Users Meeting

Drell-Yan Projection

6/17/2014 25

μ

μ


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


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


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


Users Meeting

6/17/2014


Users Meeting

29

ThanksThanksThanksThanks

6/17/2014


Users Meeting

30

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


Users Meeting

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


Users Meeting

32

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


Users Meeting

33

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


Users Meeting

34

� 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

6/17/2014


Users Meeting

35

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


Users Meeting

Forward AN

for Charged Hadrons

6/17/2014 37

� Measured at Muon Arms

1.2<|η|<2.4

� No PID – Unidentified

charge hadrons

h+/-


Users Meeting

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 ,


Users Meeting

transverse spin results from phenix at rhic · pdf filetransverse spin results from phenix at...

Documents