naohito saito, kyoto university first results from rhic spin program and future prospects spin 2004...

Naohito Saito, Kyoto UniversityNaohito Saito, Kyoto University

First Results from RHIC Spin Program First Results from RHIC Spin Program and Future Prospectsand Future Prospects

Spin 2004 October 11-16, 2004, Trieste, ItalySpin 2004 October 11-16, 2004, Trieste, Italy

Naohito SaitoNaohito Saito

Kyoto UniversityKyoto University


OutlineOutline

Spin Structure of the Nucleon from Global QCD Spin Structure of the Nucleon from Global QCD AnalysisAnalysis

RHIC Spin Program RHIC Spin Program First ResultsFirst Results

– Gluon Polarization in the ProtonGluon Polarization in the Proton– Single Transverse Spin AsymmetrySingle Transverse Spin Asymmetry– pp/pC Elastic Scatteringpp/pC Elastic Scattering– Neutron asymmetryNeutron asymmetry

Future ProspectsFuture Prospects UpgradesUpgrades SummarySummary


““Proton Spin Crisis” Proton Spin Crisis” EMC PLB & NP (1988)EMC PLB & NP (1988)

Proton Spin carried Proton Spin carried by Quark Spin is by Quark Spin is ZERO??ZERO??– Gluon SpinGluon Spin？？– Orbital MotionOrbital Motion？？

2

1J

orbital:

onpolarizatigluon :

2

1

2

1

Lz

g

SDU

Lzgproton

0

200

400

600

800

1000

1200

1 3 5 7 9 11 13 15 171990

19952000

1215 Citations!! (as of 28/9/04)

T. Nakano et al. + paper 325 citations


Parton Distribution FunctionsParton Distribution Functions Quark DistributionQuark Distribution

q(x,Q2)=

q(x,Q2)=

q(x,Q2)=

=

unpolarised distributionunpolarised distribution

helicity distributionhelicity distribution

transversity distributiontransversity distribution

g(x,Q2)=

g(x,Q2)=

No Transverse Gluon Distribution in 1/2

Gluon DistributionsGluon Distributions


Precision Data from DISPrecision Data from DIS Precision Data in Precision Data in

Wide Kinematical Wide Kinematical RangeRange– QQ22 evolution agrees evolution agrees

with pQCDwith pQCD

NotesNotes：：– Only Fixed Target Only Fixed Target

Spin Experiments Spin Experiments so far…so far…

– Need a Collider to Need a Collider to extend kinematical extend kinematical coveragecoverage

Q2 (GeV2)

g1


Polarised PDFPolarised PDFAAsymmetrysymmetry A Analysis nalysis CCollaboration ollaboration

M. Hirai, S. Kumano and N. Saito, PRD (2004)M. Hirai, S. Kumano and N. Saito, PRD (2004) Valence Dist’s Valence Dist’s

are determined are determined wellwell

Sea Dist’ is Sea Dist’ is poorly poorly constrainedconstrained

Gluon can be Gluon can be either >0, =0, <0either >0, =0, <0

Even if we Even if we assume assume gg((xx))=0, =0, Chi-square Chi-square changes only changes only 2.5%2.5%– Sea quark error Sea quark error

is reducedis reduced

Error size in the previous plot

Error size in the previous plot


RHIC Spin Physics ProgramRHIC Spin Physics Program Accelerate and Collide Polarized Proton Accelerate and Collide Polarized Proton

Beams with Hi-Polarization and LuminosityBeams with Hi-Polarization and Luminosity

Brief HistoryBrief History– 1990: Polarized Collider WS in Penn-State U1990: Polarized Collider WS in Penn-State U– 1991: RHIC Spin Collaboration Formed1991: RHIC Spin Collaboration Formed– 1993: PHENIX and STAR integrated Spin 1993: PHENIX and STAR integrated Spin

ProgramProgram– 1995: RIKEN-BNL Collaboration (~$20M) 1995: RIKEN-BNL Collaboration (~$20M) – 2002: First Polarized Proton Collision!2002: First Polarized Proton Collision!– Significant supports from KEK, DOE and NSF Significant supports from KEK, DOE and NSF

1232max scm102,GeV500,200%,70 LsPB


What Do We Measure at RHIC?What Do We Measure at RHIC? We measure spin asymmetries for cross sectionsWe measure spin asymmetries for cross sections AALLLL: double helicity asymmetry: double helicity asymmetry

– Useful in extracting Useful in extracting gg((xx)), , qq((xx)) etc. etc.

)()(

)()(

LLA

ATT: Transversity AN:Twist-3 etc AL:Parity Violation

And various Spin Transfer Asymmetries: DNN, DLL, etc


RHIC:The First Polarised pp ColliderRHIC:The First Polarised pp Collider

STARSTAR


RHIC Spin EvolutionRHIC Spin Evolution

BRAHMS & PP2PP

STAR

AGS

LINACBOOSTER

Pol. Proton Source500 A, 300 s

Partial Siberian Snake

Siberian SnakesSpin Rotators

200 MeV PolarimeterAGS Internal Polarimeter

Rf Dipoles

0.5 1011 Pol. Protons / Bunch

PHOBOS

RHICPHENIX

RHIC pC CNI PolarimeterLocal Polarimeter

Local Polarimeter

0.7 x1011

AGS pC CNI Polarimeter

Absolute Polarimeter (Pol-Jet Tgt)

AGS Warm Snake

AGS Cold Snake


2.5 weeks

RHIC Spin: RHIC Spin: LL and and PP Progress Progress Run 2: Run 2: AANN

– ~7nb~7nb-1-1/day/day– PPBB~20% ~20%

Run-3:Run-3:AALLLL– 10nb10nb-1-1/day/day– PPBB~26%~26%– (AGS) 40%(AGS) 40%

Run-4:Run-4:AALLLL– Only Machine Only Machine

StudiesStudies– 30nb30nb-1-1/day/day– PPBB~40%~40%– (AGS) 50%(AGS) 50%

Run-5 :Run-5 :AALLLL– Long pp Run Long pp Run

plannedplanned

>4 weeks

>4 weeks

4 days

4 days


Run-4 Achievements (5+1 weeks)Run-4 Achievements (5+1 weeks) Improved Polarisation at AGS Improved Polarisation at AGS

– With a new Helical Snake: 40% With a new Helical Snake: 40% 50 % 50 %– Further improvement with additional snake is expected Further improvement with additional snake is expected

in Run-5in Run-5 Established a better working point at RHICEstablished a better working point at RHIC

– Previous tune ~ 0.22 Previous tune ~ 0.22 ~ 0.70 ~ 0.70– Better beam life time and polarisation observedBetter beam life time and polarisation observed

Established a vacuum improvement with NEG Established a vacuum improvement with NEG coatingcoating– Significantly higher beam current can be expected in Significantly higher beam current can be expected in

Run-5Run-5 Commissioned Polarised Gas Jet TargetCommissioned Polarised Gas Jet Target

– Need for absolute beam polarisationNeed for absolute beam polarisation Commissioned Exp’s for Hi-LuminosityCommissioned Exp’s for Hi-Luminosity

– Luminosity Monitor, DAQ, etc. Luminosity Monitor, DAQ, etc.


Pol’d Gas Jet Target for Absolute Pol’d Gas Jet Target for Absolute PPBB Polarized Hydrogen Gas

Jet Target– thickness of > 1012 p/cm2

– polarization > 90% (~95% !)– no depolarization from beam

wake fields Use a Silicon recoil

spectrometer to measure – The left-right asymmetry AN

in pp elastic scattering in the CNI region to AN < 10-3 accuracy.

Transfer this to the beam polarization– Calibrate the p-Carbon

polarimeters In (2004) the goal was to

measure PB to 10%

T. Wise and A. Zelenski in //-session 8

H. Okada in //-session 4A. Bravar (invited) in //-session 7

H. Okada and O. Jinnouchi in //-session 4


Online Plots from Pol-J-TgtOnline Plots from Pol-J-Tgt

Hor. pos. of Jet 10000 cts. = 2.5 mm

Num

ber

of e

last

ic p

p ev

ents Jet profile

FWHM ~ 6 mmAs designed

Data collected so far in this run:

• 100 GeV ~ 700,000 events at the peak of the analyzing power (~ 3 x 106 total useful pp elastic events)• 24 GeV ~ 120,000 events at the peak of the analyzing power (~ 5 x 105 total useful pp elastic events)

TD

C: 1

ct =

1.2

ns

ADC: 1 ct = 40 keVCNI peak AN 1 < E REC < 2 MeV

Recoil protons elastic pp ppscattering

prompt eventsand beam gas

sourcecalibration


PPBB in Collision Point: Local Pol. in Collision Point: Local Pol. Significant Collaboration of PHENIX-STAR Significant Collaboration of PHENIX-STAR

and Acc. Physicistsand Acc. Physicists

STARSTAR

J. Kiryluk in //-session 7

W. McKay on Friday

http://www.phenix.bnl.gov/


Precision QCD test for Hadron PrdctnPrecision QCD test for Hadron Prdctn pppp 00 X @ 200 X @ 200

GeV (PHENIX)GeV (PHENIX) Cross Section is Cross Section is

well described by well described by the pQCD over 8 the pQCD over 8 order of order of magnitude!magnitude!

STAR STAR 00 Results Results also agree!also agree!

PHENIX PRL (2004)

Good agreementwith NLO pQCD

J.Sowinski’s talk

STARSTAR



ForwardForward Inclusive Cross SectionInclusive Cross Section

STAR data consistent with Next-to-Leading Order pQCD calculations

in contrast to data at lower s (Bourelly and Soffer, Eur.Phys.J. C36 (2004) 371-374)

• STAR data at

= 3.8 (hep-ex/0310058, Phys. Rev. Lett. 92 (2004) 171801)

• = 3.3 (hep-ex/0403012, Preliminary)

• NLO pQCD calculations at fixed with equal factorization and renormalization scales = pT

• Solid and dashed curves differ primarily in the g fragmentation function

STARSTAR


First Prompt First Prompt Results @ 200 GeV Results @ 200 GeV

RHIC Spin Gold RHIC Spin Gold plated mode for plated mode for g started! g started!

pQCD describes pQCD describes results very well!results very well!

Ready for Ready for AALLLL!!

See talk by K. See talk by K. Okada in //-Okada in //-session 2session 2

Xpp



gqgq G

G

q

q

qqqqq

q

q

q

gggg G

G

G

G

ALL

Constraints on Constraints on gg((xx)) w/ w/ 00 Production Production pppp 00 XX is sensitive to is sensitive to gggggggg and and gqgqgqgq

PHENIX Results from Run-3To Appear in PRL

GeV 200at on tocontributi fractional 0 sXpp GeV 200at for :PHENIX 0 sXppALL

-> Y. Fukao’s talk in //-session 2



AALLLL((00) and ) and g/g(x)g/g(x) Pion Production: Pion Production:

Mixture of gg+gq+qqMixture of gg+gq+qq

)()()(

)()(

)()(

)()()(

)()()(

)()(~

2

2

2

xd

dx

u

uududaR

xd

dddddaR

xu

uuuuuaR

xd

dx

g

ggdgdaR

xu

ux

g

gguguaR

xg

gggggaRA

LLud

LLdd

LLuu

LLgd

LLgu

LLggLL

gqgq

qqqq

gggg


-> Y. Fukao’s talk in //-session 2


Gluon Polarization in the ProtonGluon Polarization in the Proton Hunting for Hunting for gg

– Direct ProbeDirect Probe FNAL E704 FNAL E704

– High-pT High-pT 00

– High-mass Multi-High-mass Multi-pairpair DESY HERMESDESY HERMES

– High-pT hadron pairHigh-pT hadron pair

– Indirect ProbeIndirect Probe NLO Analysis by SMCNLO Analysis by SMC

PLB261(1991)197

PLB336(1994)269

PRD58(1998)112002

PRL 84(00)2584


STARSTAR Reconstructs jets in Large d

(~1/10 of these stats from 2004 currently being processed)

J. Sowinski’s talk


g/gg/g((xx)) Now and Future Now and Future New COMPASS New COMPASS

results!results! PHENIX PHENIX 00

– Need global QCD Need global QCD analysisanalysis

Coming soon Coming soon from RHIC are…from RHIC are…– PHENIX PHENIX 00

– STAR jet & STAR jet & 00

– Prompt Prompt – Charm/BottomCharm/Bottom

AndAnd– COMPASS charmCOMPASS charm– HERMES HERMES

deuterondeuteronCourtesy Vogelsang and Stratmann

Y. Fukao’s talk in //session-2

J. Sowinski and A.Ogawa’s talk in //session-2

K. Okada’s talk in //session-2

R. Hobbs’s talk in //session-2


Prompt Photon ProductionPrompt Photon Production Gluon Compton DominatesGluon Compton Dominates

– 10% Contamination from Annihilation 10% Contamination from Annihilation – No fragmentation contribution in LONo fragmentation contribution in LO

i

)()(

)(

)(

)(

22

22

1

1 qgqaxqe

xqe

xg

xgA LL

ii

ii

i

LL

10.001

P1

P2

k2

k1


Prompt Photon Production Prompt Photon Production Gold Plated mode for Gold Plated mode for gg((xx))

x-reconstructed using jet

xW. Vogelsang et al.

L. Bland

PHENIX STAR


Single Transverse Spin AsymmetrySingle Transverse Spin Asymmetry Non-zero Single Transverse Spin Non-zero Single Transverse Spin

Asymmetry (SSA) requiresAsymmetry (SSA) requires– Spin Flip AmplitudeSpin Flip Amplitude– Phase difference Phase difference

2/

2/

i

i

Spin Flip!


Single Transverse Spin AsymmetriesSingle Transverse Spin Asymmetries Fermilab E-704 reported Fermilab E-704 reported

Large AsymmetriesLarge Asymmetries AANN in in pion productionspion productions

Could be explained asCould be explained as– Transversity x Spin-dep Transversity x Spin-dep

fragmentation (Collins effect), fragmentation (Collins effect), or or

– Intrinsic-Intrinsic-kkTT imbalance (Sivers imbalance (Sivers effect) , oreffect) , or

– Higher-twist effectsHigher-twist effects– Or combination of aboveOr combination of above

Do not forget more E704 Do not forget more E704 results results

GeV 4.19at sXpp Left Right

)(

)(

)(

XppD

XppA

XppA

NN

N

N


PHENIX Results: Central RapidityPHENIX Results: Central Rapidity ZERO asymmetry:ZERO asymmetry:

Charged hadrons

Neutral pions

h- h+

Polarization scaling error ~30% not included

0

PHENIX Preliminary

PHENIX Preliminary

AN for both charged hadrons and neutral pions consistent with zero.


STAR Results: Forward RapiditySTAR Results: Forward Rapidity Large Asymmetry Large Asymmetry

MeasuredMeasured To distinguish models, To distinguish models,

jet axis reconstruction is jet axis reconstruction is requiredrequired

Probably…Probably…AANN requires requires large large xxBJBJ, which is only , which is only achievable in hi-achievable in hi-ppTT in in Central rapidity (small Central rapidity (small xsection)xsection)

Global Analysis with Global Analysis with HERMES results would HERMES results would be beneficialbe beneficial– Factorization has to be Factorization has to be

proven!!!proven!!!


STARSTAR

STAR new Results on STAR new Results on AANN

Significantly Significantly extended extended kinematical kinematical coverage:coverage:– More FWDMore FWD– Negative xFNegative xF

g-g correlation g-g correlation small?small?

See A. Ogawa’s See A. Ogawa’s talk in //-session 2talk in //-session 2


ExploreExplore xxFF and p and pTT

h+h+ h-h-

pionpion 219K219K 216K216K

kaonkaon 46K46K 26K26K

protonproton 165K165K 17K17KIntegrated yields of , K and proton in xF range 0.15-0.35

xF and pT range of the data PHENIX and STAR to PHENIX and STAR to Explore xExplore xFF~0 and hi-p~0 and hi-pTT

STAR and BRAHMS to STAR and BRAHMS to explore hi-xexplore hi-xFF and and lo~mid-plo~mid-pTT

BRAHMS data being BRAHMS data being analysed…analysed…

STARSTAR


AANN in in pp pp pppp and and ppCCppCC Hadronic Spin Flip Exist : Hadronic Spin Flip Exist : ppC >> C >> pppp

GeV 200 E704 FNAL

GeV 100Jet -pol RHIC

beam

beam

P

P

preliminarypppp

preliminary

GeV 100

GeV 22

beam

beam

P

P

CC pp

r5=0

H. Okada’s talk in //session-4 O. Jinnouchi’s talk in //session-4


Hadron Spin Hadron Spin Flip existsFlip exists

Indicating Indicating hiE>loE???hiE>loE???

Need to Need to Explore!!!Explore!!!

See See I.Alekseev’s I.Alekseev’s talk in talk in //session-4!//session-4!

AANN in in pp pp pppp in Hi-Energy in Hi-Energy

Statistical errors only

GeV 200@ spppp


AANN in FWD neutron production in FWD neutron production Large Asymmetry discovered (~3mrad) : Large Asymmetry discovered (~3mrad) : AANN~ -10%~ -10% Xsection(ISR) reproduced with OPE=Fully Spin Xsection(ISR) reproduced with OPE=Fully Spin

Flip!Flip!

deg0~@nXpp


onpolarizati 70%with

GeV 500at pb800

GeV 200at pb320

assuming

1

1

sLdt

sLdt


W Production in pp CollisionsW Production in pp Collisions WW is produced through pure V-A is produced through pure V-A

– Chirality is fixed Chirality is fixed ideal for spin structure studies ideal for spin structure studies

WW couples to weak charge ~ flavor couples to weak charge ~ flavor– Flavor is (almost) fixed Flavor is (almost) fixed ideal for flavor structure ideal for flavor structure

studiesstudies

Parity Violating Asymmetry Parity Violating Asymmetry AAL L ::

)()()()(

)()()()(

baba

babaWL xuxdxdxu

xuxdxdxuA

J. Soffer et al.


Sensitivity GoalSensitivity Goal Studies with PHENIX Studies with PHENIX

Muon ArmsMuon Arms– STAR Endcap STAR Endcap

Calorimeter provides Calorimeter provides similar sensitivitysimilar sensitivity

– AALL~~u/u(x)~u/u(x)~0.7-0.9 (!) at 0.7-0.9 (!) at large-large-xx

– Central Rapidity covered Central Rapidity covered by both PHENIX and by both PHENIX and STARSTAR


RHIC Spin and HERMES SIDISRHIC Spin and HERMES SIDIS Complementary!Complementary!

– RHIC WRHIC W No fragmentation No fragmentation

ambiguityambiguity xx-range limited-range limited Useless for Useless for

transversity studiestransversity studies Otherwise Otherwise WWRR!!

– HERMES Semi-HERMES Semi-Inclusive DISInclusive DIS Wide Wide xx-range-range Could be used for Could be used for

transversity studiestransversity studies


Transversity MeasurementsTransversity Measurements Drell-Yan Production of Lepton PairsDrell-Yan Production of Lepton Pairs

– Clean, but low statistics (Clean, but low statistics (QEDQED process) process) – Precision will be improved by Precision will be improved by LL upgrade upgrade

ii

ii

TTTT xqxqe

xqxqeaA

)21()()(

)21()()(

212

212

PHENIX Muon200 GeV

O. Martin, A. Schaefer, M. Stratmann, W. Vogelsang PRD60 (99) 117502


Transverse Jet ProductionTransverse Jet Production Advantages:Advantages:

– Enormous yield could Enormous yield could overcome the smallness overcome the smallness of asymmetriesof asymmetries

– No mixture with Gluonic No mixture with Gluonic contributioncontribution

Caveats:Caveats:– Control of systematics Control of systematics

will be the key for the will be the key for the successsuccess AATTTT~0.2% = 0.1% (if ~0.2% = 0.1% (if

PPBB=70%)=70%)

– AATTTT is cos2 is cos2 moment: moment: statistics will be divided statistics will be divided into several into several -bins-bins


Single Transverse Spin AsymmetriesSingle Transverse Spin Asymmetries If we have analyzer of final state quark If we have analyzer of final state quark

polarization…polarization…– We can use Spin We can use Spin Transfer Double Transfer Double Spin Asymmetry Spin Asymmetry to probe Transversity!to probe Transversity!

Spin Dep. Frag. Fn.Spin Dep. Frag. Fn. Can be studied in Can be studied in e+e- collisionse+e- collisions BELLEBELLE HERMES IFFHERMES IFF

Spin Transfer Double Spin Asymmetry

- 1

- 0.8

- 0.6

- 0.4

- 0.2

0

0.2

0.4

0.6

0.8

1

- 1 - 0.5 0 0.5 1

cos q

aTT(if)

qgqqqq'qqbarFn.) Frag. Dep.Spin (

)(1

if

TTT axhA


Searches for New PhysicsSearches for New Physics Anomalous Parity Violation Anomalous Parity Violation

in Jet Production in Jet Production – Contact Interaction (Scale Contact Interaction (Scale ))

CDFCDF>1.8 TeV (obsolete)>1.8 TeV (obsolete) D0 D0 >2.4 TeV (obsolete)>2.4 TeV (obsolete) RHIC Spin Reach RHIC Spin Reach ~3.3 TeV~3.3 TeV

– New Gauge Boson Z’New Gauge Boson Z’ Need higher energy to Need higher energy to

provide useful informationprovide useful information But see T.Gehrmann’s new But see T.Gehrmann’s new

workwork


RHIC Spin RoadmapRHIC Spin RoadmapYearYear P(%)P(%) WeeksWeeks

(Com/Ph)(Com/Ph)

LumiLumi CM CM EnergyEnergy

Goals Goals

20022002 2020 8 (5/3)8 (5/3) 0.15 pb0.15 pb-1-1 200 GeV200 GeV Transverse Spin Transverse Spin

Systematic StudiesSystematic Studies

20032003 3030 8 (5/3)8 (5/3) 0.35 pb0.35 pb-1-1 200 GeV200 GeV Longitudinal SpinLongitudinal Spin

Gluon Polarization?Gluon Polarization?

20042004 5050 5(5/0) 5(5/0)

0.15 pb0.15 pb-1-1 200 GeV200 GeV RHIC Commissioning RHIC Commissioning

Polarized Gas Jet TargetPolarized Gas Jet Target

20052005 6060

10 pb10 pb-1-1 200 GeV200 GeV

500 GeV500 GeV

Gluon Gluon Polarization/Transv.Polarization/Transv.

Commissioning-1?Commissioning-1?

2006/72006/7 7070

~100 pb~100 pb-1-1

pbpb-1-1

200 GeV200 GeV

500 GeV500 GeV

Gluon Gluon Polarization/Transv.Polarization/Transv.

Commissioning-2?Commissioning-2?

2008/92008/9 7070 ~350 pb~350 pb-1-1 500 GeV500 GeV W-Physics/Transv.W-Physics/Transv.

PHENIXPHENIX STARSTAR

Fwd Cal, MRPC-TOFFwd Cal, MRPC-TOF

VTX, Muon Trigger, VTX, Muon Trigger, Fwd CalFwd Cal

DAQ/FEE-1KHz, DAQ/FEE-1KHz, HFT, Fwd TrkerHFT, Fwd Trker

M.Togawa, E. Kinney and J.Sowinski’s talk in //session-2


Hadron Collider Physics

TEVATRON LHC

Growing Fields…Growing Fields…

RHIC-SpinGluon PolarizationQuark PolarizationTransversityPol. FragmentationRole of Strangeness

Precision Structure Studies

Ongoing Spin Experiments COMPASS,HERMES JLab

Ongoing Unpolarized Studies HERA-II

Future Projects J-Parc,GSI -Factory?

EIC (ep, eA)? JLab-12?

Mechanism of Confinement Lattice-QCD、 Effective Model

N elastic scattering

e+e- Data … LEP, BELLE

Hi-E Heavy Ion Physics RHIC, LHC

Dark Matter

Neutron EDM

Precision,small-xLarge-x

Large-x


SummarySummary After a decade of efforts, RHIC Spin started to After a decade of efforts, RHIC Spin started to

produce physics resultsproduce physics results– Precision QCD tests (Precision QCD tests (00, prompt photon xsection), prompt photon xsection)– Gluon polarization by Gluon polarization by 00/Jet/Jet production production– Single transverse spin asymmetriesSingle transverse spin asymmetries

Inclusive hadron productionInclusive hadron production pp/pC elastic scatteringpp/pC elastic scattering

Run-4 commissioning was very successful Run-4 commissioning was very successful – Machine/Pol-Jet/ “Unexpected” Physics resultsMachine/Pol-Jet/ “Unexpected” Physics results

More excitements are coming soon!More excitements are coming soon!– Theorists: predictions are welcome (rather than post.) Theorists: predictions are welcome (rather than post.) – Experimentalists: join to share excitement! Experimentalists: join to share excitement!

“Prospects for Spin Physics at RHIC” G. Bunce, N. Saito, J. Soffer and W. Vogelsang

Ann. Rev. of Nucl. And Part. Science 2000


Future UpgradesFuture Upgrades – Inner and Forward Tracking – Inner and Forward Tracking u(x)d(x)

_ _

Parity violating long. asymmetry in W production allows extraction of

ALW- ~ u(x1)d(x2)+d(x1)u(x2)

_ _

Polarized q Flavor Asymmetryrelated to the nature of the sea

_

Large d-u_ _

Nadolsky and Yuan, Nucl. Phys. B666 (2003) 31.

3-layer Si strip barrel and pixel detector

Si planes and GEM for forward tracking

• Sensitivity in forward region• Requires tracking for up to

pT~40 GeV e+/e- sign determination

• Tracking upgrade

STARSTAR

AL


ΔΔｓの測定の意義ｓの測定の意義核子のスピン構造の精密な理解核子のスピン構造の精密な理解

–フレーバーＳＵ（３）仮定を超えてフレーバーＳＵ（３）仮定を超えて中性子ＥＤＭの問題中性子ＥＤＭの問題

–中性子ＥＤＭはクォークのＥＤＭとクォーク中性子ＥＤＭはクォークのＥＤＭとクォークの偏極に基づいて予言の偏極に基づいて予言

ダークマターの問題ダークマターの問題–ダークマターと物質の反応断面積を左右するダークマターと物質の反応断面積を左右する

smdmum

sdddudd

sdu

Es

Ed

Eu

En

)(

J.Ellis and R.A.Flores PLB377(96)83

J.Ellis and M. Karliner Lecure at Erice School 95 hep-ph/9601280

gaugino) (1) (pure )(36

5

36

17

or (photino) )(9

1

9

4)(

Usdu

sdupp


g/g(x) vs Ag/g(x) vs ALL LL and PHENIXand PHENIX

AALLLL can be only slightly can be only slightly negativenegative

PHENIX Data is only PHENIX Data is only consistent with consistent with g(x)<0g(x)<0– -0.173<-0.173<g/g(x)< -g/g(x)< -

0.040.04 Of course, this is only Of course, this is only

1-sigma statement1-sigma statement pQCD?pQCD? Similar conclusion Similar conclusion

(Only slightly negative (Only slightly negative AALLLL) reached by ) reached by Vogelsang, Stratmann, Vogelsang, Stratmann, et al.et al.

Center of scale error = 65%

Low end of scale error

Hi end of scale error


Impact of PHENIX Prompt PhotonImpact of PHENIX Prompt Photon If we include Future PHENIX Data into If we include Future PHENIX Data into

Global Analysis…Global Analysis…

AAC Pre

liminary

AAC Pre

liminary

M. Hirai et al.


Gluon Polarisation Now and MoreGluon Polarisation Now and More HERMESHERMES

– PRL84(00)2584 SMCSMC

– B. Adeva et al. hep-ex/0402010

Near FutureNear Future– COMPASSCOMPASS– RHIC RHIC

If we could If we could confirm pQCD confirm pQCD framework, framework, PHENIX PHENIX 00 and and STAR Jet would STAR Jet would contribute contribute

PHENIX 0 ALL (2.5 GeV/c)


Towards Design LuminosityTowards Design Luminosity Higher beam current and tune control are the keysHigher beam current and tune control are the keys

Run-3 Run-4 Goal Gain Remark# of bunches 55 55 120 2.2beam intensity 0.6 0.8 2.0 2.5 NEG coating to reduce e-cloudbeta* (m) 1.3 1.3 1.0 1.3emittance 10 20 20 1.0useful vertex (%) 50 50 100 2.0 200 MHz storage RF cavityNet Gain 35.5

Uptime (%) 10 50 70 1.4 improve stabilityLavg/Lpeak 0.5 0.7 1.0 1.43Net Gain 2.00

Total Gain 70.91


Transiency of TransversityTransiency of Transversity Transversity is Detectable only in combination Transversity is Detectable only in combination

with other function even in Lepton Scatteringwith other function even in Lepton Scattering– Chiral-odd transversity should be multiplied by Chiral-odd transversity should be multiplied by

another chiral-odd function (= mostly unknown)another chiral-odd function (= mostly unknown)

Requires Trans-world efforts covering Trans-Requires Trans-world efforts covering Trans-reaction data set reaction data set

– Universality of functions is crucial ! Universality of functions is crucial ! Applicability of Factorization Theorem should be clarifiedApplicability of Factorization Theorem should be clarified

21

sin

1211

11

11sin

))(()(

...)(),()()(

)()()(

...)()()'(

zHXeeA

zHxxexhXppA

xhxhXllppA

zHxhXeepA

T

N

TT

UT


““Analyzing Power” of pp CollisionsAnalyzing Power” of pp Collisions Quark and Gluon Quark and Gluon

contribute to acontribute to aLLLL

Only Quark contributes Only Quark contributes to ato aTT TT and smalland small


Transverse Drell-Yan Transverse Drell-Yan ProductionProduction Advantages:Advantages:

– Purely transversity effectPurely transversity effect– Relatively clean Relatively clean reconstruction of reconstruction of partonic kinematics partonic kinematics (still requires (still requires co-linear approximation)co-linear approximation)

Disadvantage:Disadvantage:– Rare: electro-Rare: electro- magnetic processmagnetic process– Unknown * UnknownUnknown * Unknown

Cf. ACf. ATTTT(W+-) =0 (W+-) =0 – No right-handed currentNo right-handed current

O. Martin, A. Aschaefer, M. Stratmann, and W.VogelsangPRD57 (1998)3084


QCD Selection RuleQCD Selection Rule AATTTT/A/ALLLL<<<<11 for Jet Productionfor Jet Production

– Absence of Gluon Contribution toAbsence of Gluon Contribution to A ATTTT

– Even in Quark-Quark ScatteringEven in Quark-Quark Scattering Only Exchange channel can contributeOnly Exchange channel can contribute

Color SuppressionColor Suppression

Chiral OddChiral Even

R.L. Jaffe and NSPL B382 (1996) 165


Dead End?

NOT AT ALL!


Experimental Results of SSAExperimental Results of SSA In lower Energies In lower Energies

significant asymmetries significant asymmetries found in both Central & found in both Central & Forward regionForward region

At vs=20 GeV (E704)At vs=20 GeV (E704)– Small/zero asymmetries Small/zero asymmetries

in central region (xF~0)in central region (xF~0)– Large asymmetries in Large asymmetries in

forward (xF>>0) pion forward (xF>>0) pion productionproduction

At vs=200 GeV, againAt vs=200 GeV, again– Large Large AANN in forward in forward

– Zero Zero AANN in Central in Central


Transverse Prompt Transverse Prompt ProductionProduction

AANN: Qiu-Sterman predicted : Qiu-Sterman predicted non-zero Anon-zero ANN at x at xFF~0~0

With away-side jet With away-side jet reconstructionreconstruction– sine-moment analysis is sine-moment analysis is

possiblepossible– Partonic kinematics can be Partonic kinematics can be

reconstructedreconstructed

)(

)()(

)(

)())((

2

2

zD

zDqqga

xqe

xqeXppA

q

qifTT

q

qT

With polarized With polarized 33He, He, u-u-d d separation is possibleseparation is possible

P1

P2

k2

k1


What Do We Learn?What Do We Learn? We need more statistics! We need more statistics! pp collisions are so sensitive to pp collisions are so sensitive to gg((xx)) so that it so that it

already provides similar constraints to two decades already provides similar constraints to two decades of polarised DIS experimentsof polarised DIS experiments– (yes, our preparation also taking a decade)(yes, our preparation also taking a decade)

Caveats:Caveats:– Applicability of pQCD: Applicability of pQCD:

some confirmation with xsection measurement DONEsome confirmation with xsection measurement DONE Intrinsic-Intrinsic-kkTT, fragmentation functions, fragmentation functions

– AALLLL((00)/)/AALLLL(jet)(jet) are sensitive to are sensitive to

((gg22++ qqgg+ + qqqq) ; what about sign?) ; what about sign? It is very important to have both lepton and hadron It is very important to have both lepton and hadron

scattering data to reveal possible systematics scattering data to reveal possible systematics involved.involved.


Sivers or Collins-Heppelman?Sivers or Collins-Heppelman? AANN for Drell-Yan : only from Sivers for Drell-Yan : only from Sivers

– How about AHow about ANN for Prompt Photon? for Prompt Photon? No fragmentation contribution at LO, but in NLO…No fragmentation contribution at LO, but in NLO…

AANN for Hadron with Jet-reconstruction? for Hadron with Jet-reconstruction?– Sine moment analysis is possible?Sine moment analysis is possible?– Intrinsic kIntrinsic kTT could damage coplanarity? could damage coplanarity? kT~ a few GeV/c: linearly grow with log(s) kT~ a few GeV/c: linearly grow with log(s)

(Sterman+Collins): s=partonic CM energy(Sterman+Collins): s=partonic CM energy

– Similar possibility in photon-jet productionSimilar possibility in photon-jet production next slidenext slide


Helicity Amplitudes and PDFsHelicity Amplitudes and PDFs Parton Distribution is connected to Forward Parton Distribution is connected to Forward

Scattering Amplitude of Proton and Parton by Scattering Amplitude of Proton and Parton by Optical TheoremOptical Theorem

For Proton (spin=1/2) there are 3 possibilities For Proton (spin=1/2) there are 3 possibilities

2

= Im


Dig out Dig out g(x) & g(x) & g ! g ! Current ExperimentsCurrent Experiments

– HERMES High-pT HERMES High-pT hadron pairhadron pair

– RHIC SpinRHIC Spin Prompt Photon (+ jet) Prompt Photon (+ jet) JetJet Inclusive hadron Inclusive hadron Heavy flavor (charm, Heavy flavor (charm,

bottom, J/y …) bottom, J/y …) – COMPASSCOMPASS Open charmOpen charm High-pT hadron pairHigh-pT hadron pair

Photon-gluon fusion

Gluon ComptonGluon Fusion

Future PossibilitiesFuture Possibilities– EIC EIC – Polarized HERAPolarized HERA– TESLA-NTESLA-N


Polarised Parton DistributionsPolarised Parton Distributions Global QCD Analysis to Extract Polarized Global QCD Analysis to Extract Polarized

Quark and Gluon Distributions Quark and Gluon Distributions – ((a laa la MRST, CTEQ) MRST, CTEQ)

Four Independent Distributions are often Four Independent Distributions are often extracted – e.g. extracted – e.g. UU((xx,,QQ22)),,DD( ),( ),S S ( ),( ), g g ( )( )– In unpolarised case, even more In unpolarised case, even more

We have ONLY TWO independent We have ONLY TWO independent measurements measurements gg11

pp((xx, , QQ22) and ) and gg11nn((xx,,QQ22))

– QQ22 evolution helps? evolution helps?

gtbcssdduu ,,,,,,,,,


DIS of Lepton from NucleonDIS of Lepton from Nucleon Structure Probed by PhotonStructure Probed by Photon

– Function of Function of xx and and QQ22=-=-qq22

– ∝∝Charge SquaredCharge Squared Not distinguish Down and StrangeNot distinguish Down and Strange Insensitive to GluonInsensitive to Gluon

Objective isObjective is

Observables areObservables are

kk’

q

p

p’

PxP=

Elastic

),(9

1),(

9

4),(

9

1

2

1),(

),(9

1),(

9

1),(

9

4

2

1),(

22221

22221

QxSQxDQxUQxg

QxSQxDQxUQxg

n

p

SDU

Proton

Neutron


Separation of Pol’ Quark Dist’sSeparation of Pol’ Quark Dist’s Only two independent measurements Only two independent measurements

gg11pp((xx, , QQ22) and ) and gg11

nn((xx,,QQ22)) Separation into 3 quark dist’s relies on Separation into 3 quark dist’s relies on

– 11stst moments (employ moments (employ -decay const’s), -decay const’s), unless unless direct measurement of sea-quarkdirect measurement of sea-quark

– Different coupling with Different coupling with gg((xx)) thru thru QQ22 evolution evolution

SDU

DU

SDU

a

a

28

3),()(

2

)(

)(ln

),( 2,

2

2

2

QxqxPQ

Q

QxqNSNSq

SNS

),(

),()()(

)()(

2

)(

),(

),(

)(ln 2

22

2

2

2 Qxg

QxxPxP

xPxPQ

Qxg

Qx

Q gggq

qgqqS

Non-Singlet Quark Distribution

Singlet Quark Distribution

How much do we know about g(x)?


From From gg11((xx,,QQ22)) to to

Proton

Deuteron = Proton + Neutron

3He=Neutron

Proton

Deuteron = Proton + Neutron

3He=Neutron

053.09

1

9

4

9

1

2

1 0.119

9

1

9

1

9

4

2

111

SDUSDU np

p1

n1

p1

n1

053.09

1

9

4

9

1

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1

0.119 9

1

9

1

9

4

2

1

1

1

SDU

SDU

n

p

|017.0340.0|)(3)/(

05.025.03/2)/(

015.0718.03/2)/(

0029.02695.1)(3)/(

DFSDgg

DFSDUgg

DFSDUgg

DFDUgg

nVA

VA

pVA

npVA

Constant in front of D/3

ene

ee

epe

epen

0083.01952.02 0112.02692.1 SDUDU

Integrate over x (0,1)Integrate over x (0,1)！！

Utilize Octet Baryon Utilize Octet Baryon -Decay Constants-Decay Constants！！

– SU(2) OKSU(2) OK！！　　（　　（ Bjorken SRBjorken SR））

)046.0124.0(

138.0213.0

S

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