Transverse spin phenomena in pp and

polarized fragmentation

Akio Ogawa, BNL2006 Oct 3

2

Related Experimental Talks (7 talks)

Tuesday J.H. Lee (BNL) xF Dependent Single Spin Asymmetries for +-, K+-, p and pbar in Polarized p+p

Collisions at sqrt(s)=200 GeV and 62 GeV (Brahms) Mickey Chiu (Illinois) Single Spin Transverse Asymmetries of Neutral Pions at Forward

Rapidities in sqrt(s)=62 GeV Polarized Proton Collisions at RHIC (Phenix) Larisa Nogach (Inst. of High Energy Phys.) Measurement of Transverse Spin Effects with the

Forward Pion Detector of STAR Han Liu (New Mexico State) Transverse Single Spin Asymmetry Measurement with Heavy

Flavors in Polarized p+p Collisions at RHIC (Phenix) Jan Balewski (Indiana) Measurement of Sivers Asymmetry for Di-jets in 200 GeV pp Collisions

at STARFriday Douglas Fields (Univ. of New Mexico) kT Asymmetry in Longitudinal polarized Collisions

(Phenix) Ralf Seidl (Illinois) Chiral-Odd Fragmentation Function Measurements at Belle

Other Plenary Talks : Anna Martin (Trieste) Transverse Spin Phenomena in Lepton Scattering Harut Avakian (JLAB) Generalized Parton Distributions Alessandro Bravar (Geneva) Spin Physics in Forward Scattering

3

Related Theoretical Talks (18 Talks)Tuesday Matthias Burkardt(New Mexico State) Hadron Tomography Werner Vogelsang (BNL) Single-Spin Asymmetries Alessandro Bacchetta (DESY) Transverse-Momentum Dependent Functions in Semi-Inclusive DIS Leonard Gamberg (Penn. State) Transverse Quark Spin Effects in Azimuthal Asymmetries in SIDIS and DY Feng Yuan (RBRC) Unique Description of Single Transverse-Spin Asymmetries in DIS and Hadron Collisions Kazuhiro Tanaka (Juntendo) A New Approach For Single Transverse-Spin Asymmetries From Twist-3 Soft-

Gluon Mechanism Yuji Koike (Niigata) Single Transverse Spin Asymmetry for Semi-Inclusive Deep Inelastic Scattering Umberto D'Alesio (Cagliari) Transverse Momentum Dependent Distributions in Hadronic Collisions Cedran J. Bomhof (Amsterdam) Sivers Effect Asymmetries in Hadron-Hadron Collisions Umberto D'Alesio (Cagliari) Constraints on Gluon Sivers Distributions from RHIC ResultsThursday Anatoly V. Efremov (JINR) Collins Effect in SIDIS and in Electron-Positron-Annihilation Alexei Prokudin (Torino) Collins Effect in polarized SIDIS and e+e- Data Genis Musulmanbekov (JINR) Single Spin Asymmetry in Strongly Correlated Quark Model Hiroshi Yokoya (Niigata) Threshold Resummeation Effects in the Polarized DY mechanism Hiroyuki Kawamura (RIKEN) QCD Prediction of ATT for Small QT Dimuon Production in pp and ppbar CollisionsFriday Daniel Boer (Amsterdam) Gluon Saturation Effects On Single Spin Asymmetries Marco Radici (Pavia) Transversity and Inclusive Two-Pion Production Alessandro Drago (Ferrara) Measuring the Sea Polarization by Drell-Yan Production at Moderate

Energies

More talks on GPDs, etc….

4

s=20 GeV, pT=0.5-2.0 GeV/c

�0 – E704, PLB261 (1991) 201.�+/- - E704, PLB264 (1991) 462.

Xpp +→+↑ • At leading twist and with collinear factorization, the chiral properties of QCD predict small analyzing powers for particle production with transversely polarized protons colliding at high energies.

A Brief History…

• The FermiLab E-704 experiment found strikingly large transverse single-spin effects in p+p fixed-target collisions with 200 GeV polarized proton beam.

• Around same time, pQCD was examined and effects were found which may explain large AN by removing leading twist or collinear restriction (by going twist-3 or kT factorization).

• Recently, large transverse single-spin effects were observed in semi-inclusive electro-production experiments (DESY,CERN,JLab) as well as p+p collisions (AGS, RHIC), which also triggered advancements in theoretical understandings.

Kane, Pumplin, Repko ‘78

5

Collins mechanism: Transversity (quark polarization) * asymmetry in the jet fragmentation

Sivers mechanism: Correlation between nucleon spin and parton kT

SP

p

p

Sq kT,π

Transverse Momentum Dependent PDFs and AN

SP

kT,qp

p

Sq

Boer-Mulders mechanism:

Correlation between parton kT and parton spin * Transversity

p

pSq

kT,qSq

kT,q

unpol

Sp

Phys Rev D41 (1990) 83; 43 (1991) 261 Nucl Phys B396 (1993) 161

Boer, Mulders

6

E(z1,z2) : quark-gluon correlation at final state

G(x1,x2) : quark-gluon correlation at initial state

(co-linear factorized) Twist-3 correlation functions and AN

^

qT

d/dqT

QCD

qT<<Q

qT~Q

QCD << qT << Q

TMD

Twist3

How those two mechanisms connected ?

Q

Qui, Starman Koike

7

The Nucleon Spin Puzzle

Longitudinal 1/2 = 1/2 + G + LL

~0.6 from EJ-sum rule~0.2 from DIS“spin crisis”

RHIC Spin & SIDIS DVCS

Spin Sum Rules

Sivers DF

Collins FF from Belle SI-DIS & RHIC Spin

~0.6 from Lattice QCD No gluon

“Recovery” of EJ-sum rule?

Transverse 1/2 = 1/2 LT Bakker, Leader, TruemanPhys.Rev.D70:114001,2004

8

Cross section at forward rapidity, NLO pQCD and AN

PRL 92, 171801 (2004)

√s=200 GeV, <η> = 3.8

nucl-ex/0602011

Cross-section is consistent with NLO pQCD calculations

Asymmetry revealed at lower energiespersists at √s=200 GeV

STARSTAR

BRAHM

S

Preliminary

9

While at fixed target energy, it was not case….

Cross-section is NOT consistent with NLO pQCD calculations

√s=23.3GeV

s=20 GeV, pT=0.5-2.0 GeV/c

�0 – E704, PLB261 (1991) 201.�+/- - E704, PLB264 (1991) 462.

Bourrely and Soffer (hep-ph/0311110, Data references therein)

10

New Insights from Recent Theoretical Works

• Transverse spin sum rule (BLT sum rule) in spin2004 Phys.Rev.D70:114001,2004

• Relation between TMD PDF and Twist-3 Correlation Function• TMD = kT factorization twist-2 qT << Q

Twist3 = co-linear factorization twist-3 QCD << qT ~ Q

Those 2 agrees at QCD << qT << Q Connection at moment:

Sivers DF “Modified” Universality, “Un-modified” “Gauge link” factor

1 for SIDIS -1 for DY 1/2 for q-q, factors for others sub-processes were calculated

Corresponding parts can be found in Twist-3 within “hard part”

Bacchetta, Bomhof, Mulders, Pijlman

Collins; Belitsky, Ji, Yuan; Boer, Mulders, Pijlman

Ji, Qiu, Yuan, Vogelsang

11

New Insights from Recent Theoretical Works

Hadron tomography with impact parameter dependent PDF and connection to Sivers DF Burkardt

Gluon Saturation & AN 　　 Boer, Dumitru,Hayashigaki

Rich phenomenology to fit data & make predictions By both TMD and Twist-3 framework For AN of , k, p, jet, photon, J/psi, D, DY… For xF, pT, sqrt(s) dependences For SIDIS data For e+e- dataYuan, Vogelssang, D'Alesio, Anselmino, Qui, Starman, Koike, Goek, Efremov, Prokudin, Melis, Murgia, Kouvaris…

Theorists are not Oracles and of course couldn’t know new results shown at this conference before they made the talk….. And we have new & exciting experimental results shown at this conference!!!

12

New Experimental Results

Hermes + Compass + Jlab (See Next Talks)

Collins FF

STARSTAR AN(xF,pT) for inclusive 0

AN for Di-jet

AN for inclusive +-

AN for inclusive K+-

AN for inclusive p+-

AN for inclusive 0

AN for J/psi

kT Asymmetry with Longitudinally Polarization

Great success of run6 L~1/pb/day P~60%

13

π0 AN at √s=200 GeV : xF-dependence

• AN at positive xF grows with increasing xF

• AN at negative xF is consistent with zero

• Run 6 data at <η>=3.7 are consistent with the existing measurements

• Small errors of the data points allow quantitative comparison with theory predictions

• Theory expects the reverse dependence on η

STARSTAR

Nogach

14

AN(pT) at xF > 0.4

Run3+Run5 data (hep-ex/0512013):

Run6 data:

• more precise measurements

• consistent with the previous runs in the overlapping pT region

• complicated dependence on pT

• Online calibration of CNI polarimeter• Hint of AN decrease with increasing pT at pT~1-2 GeV/c

residual xF-dependence? => AN mapping in (xF,pT) plane is required

STARSTAR

Nogach

15

AN(pT) in xF-bins

• Combined data from three runs at <η>=3.3, 3.7 and 4.0

• In each xF bin, <xF> does not significantly changes with pT

• Measured AN is not a smooth decreasing function of pT

as predicted by theoretical models

STARSTAR

Nogach

16

AN at 200 GeV

2.3 deg 4.0 deg

2.3 deg2.3 deg

+- +-

+- +-

Lee

17

2.3 deg 4.0 deg

2.3 deg2.3 deg

+- +-

+- +-

Twist-3 calculation provide by F. Yuan

Lee

18

AN at 62 GeV

2.3 deg 2.3 deg

2.3 deg

+- +-

+-

Lee

19

Twist-3 calculation provide by F. Yuan

2.3 deg 2.3 deg

2.3 deg

+- +-

+-

Beautiful data

- |AN(-)| is bigger than AN(+) ?- AN(-) is as large as AN(+) ?- Anti proton?

Lee

20

AN for J/psi

Disfavor the maximum contributionof gluon Sivers function

Phys. Rev. Lett. 95(2005)202001PHENIX

AN of Mid-rapidity Neutral Pions and Charged Hadrons are very well constraint to ~0.

AN for 0 from Muon Piston Calorimeter is coming very soon!

Liu

21

Going Beyond Inclusive Measurements

Inclusive DIS Not sensitiveSemi-Inclusive DIS Collins, Sivers and more

Inclusive hadron production in pp Collins and Sivers are mixed“Semi-Inclusive” pp

• p+p -> jet -> hadron + rest of jet Collins x Transversity• p+p -> di-hadron (near side) Collins x Transversity

(Interference FF)• p+p -> jet Sivers• p+p -> photon Sivers• p+p -> di-jet, di-hadron (far side) Sivers• p+p -> l+l (DY) Sivers“Asymmetric jet correlations”

in ppjet jet X

Boer & Vogelsang (PRD 69)Cedran, Yuan

22

Measured Sivers AN for Di-jets vs. Theory

• Model w/o hadronization, integrated over STAR , 5<pT<10 GeV/c, includes only quark Sivers -- predicts AN ~ AN

HERMES where q Sivers dominates• Sign of predictions reversed to adhere to Madison AN sign conventio

STAR measured AN all consistent with zero both quark and gluon Sivers effects much smaller in pp di-jets than in HERMES SIDIS !!

Emphasizes (80%+) gluon Sivers

Emphasizes (50%+ ) quark Sivers

STARSTAR

Balewski

23

kT Asymmetry in Longitudinally Polarized pp

Like Hekicity Unlike Hekicity

Large impactparameter

Head on

Orbital angular momentum may cause double spin asymmetry in width of di-jet after averaged over impact parameter

D. Fields’s Talk on Friday

24

Collins asymmetries

547 fb-1 charm corrected data sample,

UL and UC double ratios x

PRELIMINARY

PRELIMINARY

A0 (cos(2)) moments A12 (cos()) moments

R. Seidl’s Talk on Friday

25

Forward Meson Spectrometer (FMS)

• FMS will provide full azimuthal coverage for range 2.5 4.0

• Broad acceptance in xF-p

T plane for inclusive ,

etc…production in p+p and d(p)+Au

• Broad acceptance for and from forward jet pairs to probe low-x gluon density in p+p and d(p)+Au collisions

STARSTAR

Muon Piston Calorimeter (MPC)

MPC will provide full azimuthal coverage for range 3.1 3.7 and 2 < E() < 25GeV

Raw AN() of from run6 MPCNorth side is being installed now

Chiu

26

Summary

New precise data of inclusive hadron AN from RHIC Mapping AN in xF, pT and sqrt(s) Various channels : 0, +-, K +-, p +-, J/psi

Going beyond inclusive hadron measurements Sivers DF measurement with di-jet production

New measurement of polarized FF Large Collins FF observed by Belle

Great advancements in theoretical understandings Relation between TMD and Twist-3 DF is now clearer Sivers DF “universality” Frameworks to fit & predict asymmetries for SIDIS &

pp & ee

27

Questions for next 2 years

Can we understand AN(xF,pT,sqrt(s))?

Can we understand AN of K-? Can we understand proton/Anti-proton? Can we understand Sivers DF from Hermes vs STAR? Will we see AN from “jet” & photon production? Will we see Transversity * Collins FF (and BM * Collins FF) in jet

production? Will we see interference FF from Belle? Is Collins FF really universal? Formal factorization? Can we get to orbital angular momentum contribution to

nucleon spin from those measurements? Can Global fit & Extraction of DFs/FFs from DIS, pp and ee

done? GSI? J-PARC? LHC?

Burkardt; Brodsky, Hwang, Schmidt; Ji, Ma; Sivers

28

The Nucleon Spin Puzzle

Longitudinal 1/2 = 1/2 + G + LL

~0.6 from EJ-sum rule~0.2 from DIS“spin crisis”

RHIC Spin & SIDIS DVCS

Spin Sum Rules

Sivers DF

Collins FF from Belle SI-DIS & RHIC Spin

~0.6 from Lattice QCD No gluon

“Recovery” of EJ-sum rule?

Transverse 1/2 = 1/2 LT Bakker, Leader, TruemanPhys.Rev.D70:114001,2004

Backup

30

Boer-Mulders mechanism:

Correlation between parton kT and parton spin * Collins FF

p

p

Sq

kT,qSq

kT,q

unpol

kT,h

kT,h