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Quarkonium Production at J-PARC

• Quarkonium Production at J-PARC with Unpolarized Proton Beam

• Quarkonium Production at J-PARC with Polarized Beam and Target

• Calculations of charm and J/Ψ production from Yuan Feng

Jen-Chieh Peng

J-PARC Meeting for Spin and Hadron Physics RIKEN, April 7-8, 2008

University of Illinois at Urbana-Champaign

Outline

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Physics with quarkonium production at J-PARC

/ production mechanism at J-PARC energies -- is it dominated by quark-antiquark annihilation or gluon-

/ production with unpola

gluon fusion? Nuclear

riz

de

ed proton b

pendence of

e

a

/ p od

u

m :

r

JJ

J

/ Production with polarized bea

ction Antiquark distributions in nucleons and nuclei Polarization of / and

Sivers quark distribution with single-spin asymmetry m

Sea-q

/target

uark p

:

olariN

J

AJ

zation with double-spin asymmetry Quark transversity distributions with double-spin asymmetry

LL

TT

AA

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J/Ψ Production at J-PARC Energies

Very few data for J/Ψ production at 30-50 GeV

Schub et al., Fermilab E789, PR D52 (1995) 1307

• 24 GeV/c at CERN-PS

• 70 GeV/c at IHEP

2( / ) ; where /Bp N J x Ae M s

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Color-Evaporation Model for J/Ψ Production2

1

2 2 2 1/ 2

2 2

1

2

1

1

2

2

wher

: threshold,: open charm t

e /

/ ( / ) 2

a

( , ; )

nd

hresho

/(

ld

4 )F PT

F

F

m

d dx J F d

s x x x

H x x m x

QQ

21 2 1 2

, ,

22

2

1

21( ) ( )

(

{ ( ) ( ) ( ) ( )} ( ; )

,

( ;

; )

)i i i iP T P T

i u

T

s

PT

d

PG x G x

q x q x q x q

gg QQ

x

H x

m

m

q QQ

m

q

x

Gluon-gluon fusion

Quark-antiquark annihilation

CEM calculations versus data

Schuler, Vogt, PL B 387(1996)181

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J/Ψ Production at 30 GeVAt 800 GeV, J/Ψ production is

dominated by gluon-gluon fusionAt 30 GeV J/Ψ production is dominated

by quark-antiquark annihilation

J/Ψ production at 30 GeV is sensitive to quark and antiquark distributions

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Evidence that gluon-gluon fusion is the dominant mechanism at 800 GeV

800 ( ) / ( )GeV p d X p p X

1/ 2 [1 ( ) / ( )]:

/

21/ 2 [1 ( ) / ( )], :2

pd pp

pd ppn p

Drel d xl Yan

J

u x

g x g x

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Evidence that gluon-gluon fusion is the dominant mechanism at 800 GeV

800 ( ) / ( )GeV p d X p p X

1/ 2 [1 ( ) / ( )]:

/

21/ 2 [1 ( ) / ( )], :2

pd pp

pd ppn p

Drel d xl Yan

J

u x

g x g x

E866 collaboration: PRL 100 (2008)

062301

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is a sensitive test for the

( /pr

)oduction mechanism

/ ( / )p d J p p J

u d

d u

J/Ψ production at J-PARC could be sensitive to quark/antiquark distributions!

Is quark-antiquark annihilation the dominant mechanism at 30 GeV ?

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Expected J/Ψ yields and kinematic coverage J/Ψ yields for a two-month p+d run at 30 GeV

• 1012 protons/spill

• 50-cm long liquid deuterium target

• Assume 50 percent efficiency

Expected total number of J/Ψ events: ~ 8x106

Broad coverage in xF, x1, x2, pT

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Nuclear Dependence of J/Ψ Production at 30 GeV

( ) ( )p A A p N

• 30 GeV data would provide an interesting test for the xF-scaling in J/ψ production

• Very few data exist for negative xF region

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Polarization of J/ and

2

T

L

T L

Transverse : ; helicity: 1;

Decay angular distribution in the qua

1 Longitudinal : ;

rkonium rest frame

helicity: 0; -1 Unpolarized : =2

1 cos

;

dd

3 (1) 1 (8) 3 (8) 3 (8)1 0 1

2 (1 2 / ) / (1 2 / )2

/ depends on the color - spin stat

helicity: 0, 1; 0

State:

es of the QQ pair :

Polarizatio

/ : 1/ 3.4 1/ 2 1/ 6 0

n o

/

1

f

T LL T

L T

L TT L

L T

JS S P S

QQ is sensitive to the production mechanism

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Polarization of J/Ψ E866 p + Cu → J/Ψ + x (beam dump) s1/2 = 38.8 GeV

Typical dimuon mass spectrum for various xF, pT, cosθ bins

dσ/dΩ ~ 1 + λcos2θ (extraction of λ for various xF, pT bins)

(PRL 91 (2003) 21180,hep-ex/030801, T. Chang et al.)

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Polarization of J/Ψ in p + Cu Collision dσ/dΩ ~ 1 + λ cos2θ

(λ=1: transversely polarized, λ = -1: longitudinally polarized λ = 0, unpolarized)

E866 data

hep-ex/030801

• λ is small, but nonzero

• λ becomes negative at large xF

• No strong pT dependence for λ

Polarization of Ψ’ has never been measured

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Polarization of Υ(1S),Υ(2S+3S) p + Cu →Υ + x (E866 beam-dump data)

Dimuon mass spectrum

Υ(1S)

Υ(2S+3S)

Decay angular distributions

Brown et al. PRL 86, 2529 (2001)

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Polarization of Υ(1S),Υ(2S+3S) p + Cu →Υ + x (E866 beam-dump data)

λ for D-Y, Υ(1S), Υ(2S+3S)• D-Y is transversely polarized

• Υ(1S) is slightly polarized (like J/Ψ)

• Υ(2S+3S) is transversely polarized!

• Analysis of Y polarization in p+p and p+d is underway (nuclear dependence?)

• Preliminary result shows ψ’ is also transversely polarized!

Brown et al. PRL 86, 2529 (2001)

λ

λ

pT (GeV)

xF

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Polarized proton beam at J-PARC ?

Pol. H- Source

180/400 MeV Polarimeter

Rf Dipole

25-30% Helical Partial Siberian Snakes

pC CNI Polarimeter

Extracted BeamPolarimeter

• Polarized proton beam at J-PARC with– Polarized H¯ source– RF dipole at 3 GeV RCS– Two 30% partial snakes at 50 GeV Main Ring

30 GeV50 GeV

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Large single-spin asymmetry in light meson production in polarized p-p: Sivers, Collins, and/or higher-twist effect?

FNAL-E704 Elab = 200 GeV RHIC-STAR s = 200 GeV

Single-spin asymmetry in polarized p-p collision

What is the single-spin asymmetry for J/Ψ production?

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Single-spin asymmetry in polarized p-p at J-PARC

Single-spin asymmetry (AN) can probe Sivers function – Sivers function in Drell-Yan is expected to have a sign

opposite to that in DIS

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2

( ) ( )

( ) ( )q T q q qqDY

Nq q q q qq

e f x f xA

e f x f x

- J/Ψ production could also probe the Sivers function

- Much higher statistics could be obtained in J/Ψ production

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Double-spin asymmetry in polarized p-p at J-PARC

Double-spin asymmetry (ALL) with longitudinally polarized beam/target in Drell-Yan (and J/Ψ) probe Sea-Quark polarization

21 2 1 2

21 2 1 2

[ ( ) ( ) ( ) ( )][ ( ) ( ) ( ) ( )]

a a a a aDY aLL

a a a a aa

e q x q x q x q xA

e q x q x q x q x

- J/Ψ production could also probe the Sea-Quark polarization

- Much higher statistics could be obtained in J/Ψ production

D-Y ALL at 50 GeV

GRSV

G-S

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Double-spin asymmetry in polarized p-p at J-PARC

Double-spin asymmetry (ATT) with transversely polarized beam/target in Drell-Yan (and J/Ψ) probe quark transversity distribution

- J/Ψ production could also probe the transversity distribution

- Much higher statistics could be obtained in J/Ψ production

2 2 21 1 1 2

2 2 21 2

( , ) ( , )ˆ

( , ) ( , )

q qqq

TT TTqq

e h x M h x MA a

e q x M q x M

PHENIX, s1/2=200GeV, 320 pb-1

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Summary• A rich physics program in J/Ψ production can be

carried out at the J-PARC using primary proton beam.

• J/Ψ production at J-PARC energies is expected to be dominated by quark-antiquark annihilation, similar to Drell-Yan but with much larger cross sections.

• An extensive and exciting program in spin physics can be pursued if polarized proton and polarized targets are available at J-PARC.

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Following slides are provided by Feng Yuan

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Another example:Heavy flavor production

• Heavy quarkonium production (gg channel) – ep scattering

• No SSA in color-singlet model• Final state interaction in color-octet model

– pp scattering• Only initial state interaction in color-singlet• ISI and FSI cancel out in color-octet

• Open charm or beauty – Different SSAs for charm and anti-charm

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Color-singlet model

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Final state interactions with quark and anti-quark cancel out eachother, no SSA in color-singlet model

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Color-octet model

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Final state interactions can be summarized into a gauge link to infinity, nonzero SSA

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pp scattering

05/04/23 26

•Color-singlet model: only initial state interaction, non-zero SSA•Color-octet model: initial and final state interactions cancel out, no SSA

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J/Psi Production at lower energy (JPARC or FAIR)

• Quark-channel dominates– Color-singlet: only initial state

interaction contributes, -1/2Nc relative to Drell-Yan

– Color-octet: both initial and final state interactions contribute, -(Nc^2+1)/2Nc relative to DY

05/04/23 DPN Meeting 2007 28

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JPARC prediction

• Proportional to the sum of u- and d- quark Sivers function: fitted to HERMES data, Vogelsang-Yuan 05

05/04/23 DPN Meeting 2007 29

Final A_N depends on the weight of the quark-channel contribution

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Heavy quark SSA

05/04/23 DPN Meeting 2007 30

ISI: contribute to quark and anti-quark~1/4Nc

FSI: contribute to anti-quark~2/4Nc

FSI: contribute to quark~(Nc^2-2)/4Nc

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FAIR at GSI

05/04/23 DPN Meeting 2007 31

3232

Summary• We are in the early stages of a very

exciting era of transverse spin physics studies, where the future RHIC, JLAB, JPARC, FAIR, and EIC experiments will certainly play very important roles

• We will learn more about QCD dynamics and nucleon structure from these studies, especially for the quark orbital motion