H. Avakian, INT, Nov 9 1 Harut Avakian (JLab) SIDIS at EIC SIDIS at EIC Gluons and the quark sea at high energies, INT Nov 9, 2010 TMDs and spin-orbit

H. Avakian, INT, Nov 91

Harut Avakian (JLab)Harut Avakian (JLab)

SIDIS at EICSIDIS at EIC

Gluons and the quark sea at high energies , INT Nov 9, 2010

•TMDs and spin-orbit correlations•PT-distributions•Higher twists in SIDIS•Nuclear modifications•Kaons vs pions

•MC-simulations•Projections for observables•Conclusions


Single hadron production in hard scattering

Measurements in different kinematical regions provide complementary information on the complex nucleon structure.

xF - momentum

in the CM frame

xF>0 (current fragmentation)

xF<0 (target fragmentation)

h

h

Target fragmentation Current fragmentation

Fracture Functions

xF

M

0-1 1

h

h

PDF GPD

kT-dependent PDFs Generalized PDFs

PDF

hFF

DA DA

exclusivesemi-inclusive semi-exclusive


kT-dependent PDFs and FFs: “new testament”

No analog in twist-2appear in sinmomentof ALU and AUL

quark-gluon-quark correlations responsible for azimuthal moments in the cross section

Baccetta, Diehl, Goeke, Metz, Mulders, Schlegel EPJ-2007


Electroproduction kinematics: JLab12→EIC

JLab 0.1<xB<0.7 JLab@12GeV valence quarks

EIC provides access to:

EIC

JLab12

Q2

EIC

collider experiments

H1, ZEUS 10-4<xB<0.02

EIC 10-4<xB<0.3

gluons (and quarks)

fixed target experiments

COMPASS 0.006<xB<0.3

HERMES 0.02<xB<0.3

gluons/valence and sea quarks

EIC (4x60):

•wide range of Q2 for a fixed x•wide range of PT

•small x region

•wide range of Q2 for a fixed x•wide range of PT

•small x region


SIDIS: partonic cross sections

kT

PT = p┴ +z kT

p┴

Ji,Ma,Yuan Phys.Rev.D71:034005,2005

How sensitive are SIDIS observables to x-kT correlations?


Quark distributions at large kQuark distributions at large kTT: lattice: lattice

Higher probability to find a quark anti-aligned with proton spin at large kT and bT

B.Musch et al arXiv:1011.1213

B.Pasquini et al

Higher probability to find a d-quark at large kT


Quark distributions at large kQuark distributions at large kTT: lattice: lattice

B.Musch et al arXiv:1011.1213

u/u

JMR model

q

DqMR , R=s,a

Sign change of u/u consistent between lattice and diquark model



Hadronic PT-distriutionsHadronic PT-distriutions

H. Mkrtchyan et al. Phys.Lett.B665:20-25,2008.

NJL model, H.Matevosyan


DIS vs SIDIS → additional hadron detection.

Flavor decomposition in SIDIS

Frascati, Oct 17

COMPASS data only

HERMES

COMPASS

DIS

COMPASS

HERMES

SIDIS


H.Avakian, JLab, Oct 29 11

Acceptances and efficiencies

How acceptance in and PT affect the A1 and s extractions in SIDIS?

HERMES

EIC


coscos moment in A moment in ALLLL-P-PTT-dependence-dependence

PT-dependence of cos moment of double spin asymmetry is most sensitive to kT-distributions of quarks with spin orientations along and opposite to the proton spin.

hep-ph/0608048

02=0.25GeV2

D2=0.2GeV2

CLAS PRELIMINARY


A1

A1 PT-dependence

CLAS data suggests that width of g1 is less than the width of f1

AnselminoCollins

Lattice

New CLAS data would allow multidimensional binning to study kT-dependence for fixed x

PT

PT

arXiv:1003.4549


A1 PT-dependence in SIDIS

M.Anselmino et al hep-ph/0608048

•ALL ) sensitive to difference in kT distributions for f1 and g1 •Wide range in PT allows studies of transition from TMD to perturbative approach

02=0.25GeV2

D2=0.2GeV2

Perturbative limit calculations available for :

J.Zhou, F.Yuan, Z Liang: arXiv:0909.2238


Beam SSA for exclusive pions

Sign flip at z ~ 0.5

At z>0.5 struck quark in pion

W2>4 GeV2,Q2>1 GeV2

4.3 GeV

5.7 GeV

LUND-MC

-t < 0.5GeV2

15


No x-dependence?

Change the sign at low z?

Beam SSA: ALU from COMPASS & HERMES

CLAS @4.3 &5.7GeV


SSA at large xF

ANL s=4.9 GeV

BNL s=6.6 GeV

FNAL s=19.4 GeV

RHIC s=62.4 GeV

0 moves to lower xF with energy?


Beam SSA: ALU from CLAS @ JLab

0.5<z<0.8

Beam SSA from hadronization (Collins effect) by Schweitzer et al.

Photon Sivers Effect Afanasev & Carlson, Metz & Schlegel, Gamberg et al.

Beam SSA from initial distribution (Boer-Mulders TMD) F.Yuan using h1

┴ from MIT bag model

Collins contribution should be suppressed → g┴ wanted !!!


x

PT

h

S=y

HT function related to force on the quark. M.Burkardt (2008)

Chiral odd HT-distributionChiral odd HT-distribution

How can we separate the HT contributions?

Compare single hadron and dihadron SSAs

Only 2 terms with common unknown HT G~ term!

M.Radici


Jet limit: Higher Twist azimuthal asymmetriesJet limit: Higher Twist azimuthal asymmetries

No leading twist, provide access to quark-gluon correlations

H.A.,A.Efremov,P.Schweitzer,F.Yuan arXiv:1001.5467

“interaction dependent”

Twist-2

Twist-3

First data available from lattice!


Modification of Cahn effect

•Large cosn moments observed at COMPASS

Bag model

arXiv:1001.3146

Gao, Liang & Wang

•Nuclear modification of Cahn may provide info on kT broadening and proton TMDs

total transverse momentum broadening squared


LEPTO/PEPSI: quark distributions

Need to model TMDs in LUND MC

•Implemented in PEPSI modification to LEPTO done by A. Kotzinian •Add different widths for q+ and q-

z>0.1

z>0.3

MC with Cahn

Event Generator with polarized electron and nucleon: PEPSI,….

Acceptance checkDesign parameters

Smearing/resolution routinesUse GEANT as input

Physics analysis using the “reconstructed” event sample


EIC MC simulations

Different MC used in EIC simulations are consistent (Xin Qian)


Nonperturbative TMD Perturbative region

sinLU~FLU~ 1/Q (Twist-3)

In the perturbative limit 1/PT behavior expected

Study for SSA transition from non-perturbative to perturbative regime.

EIC will significantly increase the PT range.

PT-dependence of beam SSA

4x60 100 days, L=1033cm-2s-1


sinLU(UL) ~FLU(UL)~ 1/Q (Twist-3)

1/Q behavior expected (fixed x bin)

Study for Q2 dependence of beam SSA allows to check the higher twist nature and access quark-gluon correlations.

Q2-dependence of beam SSA


Sivers effect: pion electroproduction

•EIC measurements at small x will pin down sea contributions to Sivers function

S. Arnold et al arXiv:0805.2137

M. Anselmino et al arXiv:0805.2677

GRV98, Kretzer FF (4par)

GRV98, DSS FF (8par)


Sivers effect: Kaon electroproduction

•At small x of EIC Kaon relative rates higher, making it ideal place to study the Sivers asymmetry in Kaon production (in particular K-). •Combination with CLAS12 data will provide almost complete x-range.

EIC

CLAS12


Sivers effect: sea contributions

•Negative Kaons most sensitive to sea contributions. •Biggest uncertainty in experimental measurements (K- suppressed at large x).

GRV98, DSS FF

S. Arnold et al arXiv:0805.2137

M. Anselmino et al arXiv:0805.2677

GRV98, Kretzer FF


Identification using the missing mass may be possible

detected

CLAS12

EIC4x60

FAST-MC

Kaon production in SIDIS

(p) = 0.05 + 0.06*p [GeV] %


(p) = 0.05 + 0.06*p [GeV] %

EIC 4x60 (Lumi 1033,cm-2sec-1 , ~1 hour)

K*s can be studied with EIC

<x>=0.1, <Q2>=4


H.Avakian, JLab, Oct 29 31

Kaon <cos2> @ HERMES


Collins asymmetry - proton

Is there a link between HERMES and BRAHMS Kaon vs pion moments (K- has the same sign as K+ and pi+, comparable with K+)?

“Kaon puzzle” in spin-orbit correlations


Collins effect

Simple string fragmentation (Artru model)

Leading pion out of page ( - direction )

If unfavored Collins fragmentation dominates measured - vs +, why K- vs K+ is different?

L

z

kicked in the opposite to the leading pion(into

the page)

Sub-leading pion opposite to leading (double kick into the

page)

L

33


Boer-Mulders Asymmetry with CLAS12 & EIC

CLAS12 and EIC studies of transition from non-perturbative to perturbative regime will provide complementary info on spin-orbit correlations and test unified theory (Ji et al)

Nonperturbative TMDPerturbative region

Transversely polarized quarks in the unpolarized nucleon-

CLAS12

EIC

e p5-GeV 50 GeV

sin(C) =cos(2h)

Perturbative limit calculations available for :

J.Zhou, F.Yuan, Z Liang: arXiv:0909.2238


From CLAS12 to EIC: Kotzinian-Mulders Effect

Study Collins fragmentation using transversely polarized quarks in a longitudinally polarized nucleon.

UL ~KM Transversely polarized

quarks in the longitudinally polarized nucleon

Wormgear


Pretzelosity @ EIC

•EIC measurement combined with CLAS12 will provide a complete kinematic range for pretzelosity measurements

5x50 eX

positivity bound -

+

helicity-transversity=pretzelosity

In models (bag, diquark) pretzelosity defines the OAM


Collins Effect: from asymmetries to distributions

Combined analysis of Collins fragmentation asymmetries from proton and deuteron may provide independent to e+e- (BELLE/BABAR)Information on the underlying Collins function.

need


production in the target fragmentation

xF - momentum

in the CM frame

Wide kinematical coverage of EIC would allow studies of hadronization in the target fragmentation region (fracture functions)

polarization in TFR provides information on contribution of strange sea to proton spin

Study polarized diquark fracture functions sensitive to the correlations between struck quark transverse momentum and the diquark spin.

x F(

)EIC CLAS12

(ud)-diquark is a spin and isospin singlet s-quark carries whole spin of uds

J.Ellis, D.Kharzeev, A. Kotzinian ‘96 W.Melnitchouk and A.W.Thomas ‘96


Sivers effect in the target fragmentation

A.Kotzinian

Separation of current and target fragmentation at EIC will allow studies of kinematic dependences of the Sivers effect in target fragmentation region



Fracture Functions

Mh


Summary

Studies of spin and azimuthal asymmetries in semi-inclusive processes at EIC :

•Provide detailed info on partonic spin-orbit correlations •Measure transverse momentum distributions of partons at small x, in a wide range of Q.

•Study quark-gluon correlations (HT) in nucleon and nucleus

•Need realistic MC simulations (LUND,Geant) to check sensitivity to various effects related to the transverse structure of the nucleon•Need more theory (+lattice) support for HT EIC: Measurements related to the spin, spin orbit and quark-gluon correlations combined with JLab12 HERMES,COMPASS, RHIC,BELLE,BABAR,Fermilab,J-PARC,GSI data will help construct a more complete picture about the spin structure of the nucleon beyond the collinear approximation.


Support slides….



MC simulations using NJL


M.Osipenko


kT and FSI

l l’

x,kT

proton

spectator system

•The difference is coming from final state interactions (different remnant)

Tang,Wang & Zhou

Phys.Rev.D77:125010,2008

lT

l l’

x,k’T l’T

spectator systemnucleus

total transverse momentum broadening squaredBHS 2002

Collins 2002Ji,Yuan 2002

soft gluon exchanges included in the distribution function (gauge link)


Nuclear broadening Hadronic PT-distriutionsNuclear broadening Hadronic PT-distriutions

Large PT may have significant nuclear contribution


JLab, Nov 2547

Azimuthal moments with unpolarized target

quark polarization


JLab, Nov 2548


quark polarization


JLab, Nov 2549

SSA with unpolarized target

quark polarization


JLab, Nov 2550


quark polarization


SSA with long. polarized target

quark polarization



quark polarization



quark polarization



quark polarization


Twist-3 PDFs : “new testament”


High energy quarks at small angles

Struck quark kinematics (EIC 4x60)

q


Quark distributions at large kQuark distributions at large kTT

Higher probability to find a hadron at large PT in nuclei

kT-distributions may be wider in nuclei?

PT = p┴ +z kT

bigger effect at large z


Hadronic PHadronic PTT-distriutions-distriutions

H. Mkrtchyan et al. Phys.Lett.B665:20-25,2008.


SIDIS (*p->X) x-section at leading twist

•Measure Boer-Mulders distribution functions and probe the polarized fragmentation function•Measurements from different experiments consistent

TMD PDFs


Transverse force on the polarized quarks

Interpreting HT (quark-gluon-quark correlations) as force on the quarks (Burkardt hep-ph:0810.3589)

Quark polarized in the x-direction with kT in the y-direction

Force on the active quark right after scattering (t=0)


EIC: Kinematics Coverage

Major part of current particles at large angles in Lab frame (PID at large angles crucial).

e p5 GeV 50 GeV

e’+X all

xF>0

z>0.3

EIC-MC

xF>0 (CFR)

xF<0 ( TFR)

EIC-MC


EIC medium energy

• Electron energy: 3-11 GeV

• Proton energy: 20-60 GeV

– More symmetric kinematics provides better resolution and particle id

• Luminosity: ~ 1034 cm-2 s-1

– in range around s ~ 1000 GeV2

• Polarized electrons and light ions

– longitudinal and transverse

• Limited R&D needs

• 3 interaction regions (detectors)

• Potential upgrade with high-energy ring

Main FeaturesMain Features• Electron energy: 4-20 GeV

• Proton energy: 50-250 GeV

– More symmetric kinematics provides better resolution and particle id

• Luminosity: ~ 1033 cm-2 s-1

– in range around s ~ 1000-10000 GeV2

• Polarized electrons and light ions

– longitudinal and transverse

• Limited R&D needs

• ? interaction regions (detectors)

• 90% of hardware can be reused

EIC@JLabEIC@RHIC

Slides are for a “generic” US version of an EIC (5x50 or 4x60):• polarized beams (longitudinal and transverse, > 70%)• luminosities of at least 1033


JETSET:Single particle production in hard scattering

Lund-MC should be modified to allow checks of sensitivity of measurements to different effects related to the transverse structure

- Before- After quarkTarget remnant

LUND Fragmentation Functions


Cross section is a function of scale variables x,y,z

z

SIDIS kinematical plane and observablesSIDIS kinematical plane and observables

U unpolarized

L long.polarized

T trans.polarizedBeam polarizationTarget polarization

sin2moment of the cross section for unpolarized beam and long. polarized target


Identification using the missing mass may be possible

detected

CLAS12

EIC4x60

FAST-MC

Kaon production in SIDIS

(p) = 0.05 + 0.06*p [GeV] %


JLab, Nov 2566


quark polarization


JLab, Nov 2567


quark polarization


JLab, Nov 2568


quark polarization


JLab, Nov 2569


quark polarization



quark polarization



quark polarization



quark polarization



quark polarization


Single hadron production in hard scattering

Measurements in different kinematical regions provide complementary information on the complex nucleon structure.

xF - momentum

in the CM frame



h

h

Target fragmentation Current fragmentation

Fracture Functions

xF

M

0-1 1

h

h

PDF GPD

kT-dependent PDFs Generalized PDFs

PDF

hFF

DA DA

exclusivesemi-inclusive semi-exclusive


production in the target fragmentation

xF - momentum

in the CM frame

Wide kinematical coverage of EIC would allow studies of hadronization in the target fragmentation region (fracture functions)

polarization in TFR provides information on contribution of strange sea to proton spin

Study polarized diquark fracture functions sensitive to the correlations between struck quark transverse momentum and the diquark spin.

x F(

)EIC CLAS12

(ud)-diquark is a spin and isospin singlet s-quark carries whole spin of uds


Collins effect

Simple string fragmentation for pions (Artru model)

leading pion out of page

production may produce an opposite

sign AUT

Leading opposite to leading (into page)

hep-ph/9606390 Fraction of in eX

% left from eX asm

20%

40%

~75%

~50%

Fraction of direct kaons may be significantly higher than the fraction of direct pions.

LUND-MC

L

z

L

z


K/K* and separations

Detection of K+ crucial for separation of different final states (,K*)


Sivers effect in the target fragmentation

A.Kotzinian

High statistics of CLAS12 will allow studies of kinematic dependences of the Sivers effect in target fragmentation region


27 G

eV

com

pass

herm

es JLab (upgraded)

JLab@6GeV

Q2

EIC

HERA

ENCENC

Hard Scattering Processes: Kinematics Coverage

Study of high x domain requires high luminosity, low x higher energies

collider experiments H1, ZEUS (EIC)10-4<xB<0.02 (0.3): gluons (and quarks) in the proton

fixed target experiments COMPASS, HERMES 0.006/0.02<xB<0.3 : gluons/valence and sea quarks JLab/JLab@12GeV 0.1<xB<0.7 : valence quarks

JLab

12

EIC(4

x60)

ENC(3x1

5)

Q2


Hard Scattering Processes: Kinematics Coverage

Study of high x domain requires high luminosity, low x higher energies

collider experiments H1, ZEUS (EIC)10-4<xB<0.02 (0.3): gluons (and quarks) in the proton

fixed target experiments COMPASS, HERMES 0.006/0.02<xB<0.3 : gluons/valence and sea quarks JLab/JLab@12GeV 0.1<xB<0.7 : valence quarks

27 G

eV

com

pass

herm

es JLab (upgraded)

JLab@6GeV

Q2

EIC

HERA

ENCENC

JLab12

EIC

ENC

Q2


hep:arXiv-09092238


TMDs: QCD based predictions

Large-Nc limit (Pobilitsa)

Brodsky & Yuan (2006) Burkardt (2007)

Large-x limit

Do not change sign (isoscalar)

All others change sign u→d (isovector)

Documents

H. Avakian, INT, Nov 9 1 Harut Avakian (JLab) SIDIS at EIC SIDIS at EIC Gluons and the quark sea at high energies, INT Nov 9, 2010 TMDs and spin-orbit