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Measurement of High-Mass Dimuon Production at the 50-GeV Proton Synchrotron

J-PARC Proposal P04

PAC3, July 6 – 7, 2007

Co-spokesperson:

Jen-Chieh Peng (UIUC) and Shin’ya Sawada (KEK)

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Collaboration

The Institutions

Abilene Christian University1, Argonne National Laboratory2, Duke University3, High Energy Accelerator Research Organization4, University of

Illinois at Urbana-Champaign5, Los Alamos National Laboratory6, Pusan National University7, RIKEN8, Seoul National University9, Tokyo Institute of

Technology10, Tokyo University of Science11, Yamagata University12

J.K. Ahn7, J. Chiba11, Seonho Choi9, D. Dutta3, Y. Fukao8, H. Gao3, Y. Goto8, M. Grosse-Perdekamp5, L.D. Isenhower1,

T. Iwata12, S. Kato10, S. Kumano4, M.J. Leitch6, M.X. Liu6, P.L. McGaughey6, J.C. Peng5, P. Reimer2, M. Sadler1, N.

Saito4, S. Sawada4, R. Seidl5, T.-A. Shibata10, A. Taketani8, K.H. Tanaka4, M. Togawa8, R. Towell1, H.Y. Yoshida12

Collaboration members

New collaborators are underlined

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Physics with High-Mass Dimuons at J-PARC/ Production (at 30 GeV):

/ nuclear dependence and polarization

/ flavor asymmetry via / pro

Drell-Yan (at 50 GeV):

/ flavor asymmetry at large

Antiquark distributions in nuclei

d

uction

J

J

u J

x

d

d u

Spin physics with dimuons (mostly with polarized beam/target):

Drell-Yan with polarized beam/target

(Sea-quark polarizations, transversity, Siv

Quark energ

ers functio

y los

n)

s in nucle

/ wit p a

i

h olJ

rized beam/target

(Quark polarization, transversity, Sivers function)

Unpolarized Drell-Yan decay angular distributions

(Boer-Mulder's distribution function)

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Dimuon Spectrometer for FNAL E772 / E789 / E866

p + p(d) → μ+μ- x at 800 GeV/c

Two components in the μ+μ- spectrum:

(a) Continuum: Drell-Yan process

(b) Vector mesons: J/ψ, ΥFNAL E866

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Publications of the Fermilab Dimuon ProgramE866/NuSea

• E.A. Hawker et al., Measurement of the Light Antiquark Flavor Asymmetry in the Nucleon Sea, Phys. Rev. Lett. 80, 3715 (1998) [215].

• J.C. Peng et al., d-bar/u-bar Asymmetry and the Origin of the Nucleon Sea, Phys. Rev. D58, 092004 (1998) [95].

• M.A. Vasiliev et al., Parton energy loss limits and shadowing in Drell-Yan dimuon production, Phys. Rev. Lett. 83, 2304 (1999).

• M.J. Leitch et al., Measurement of Differences between J/ and 0 Suppression in p-A Collisions, Phys. Rev. Lett. 84, 3256 (2000) [126].

• C.N. Brown et al., Observation of Polarization in Bottomonium Production at sqrt s = 38.8 GeV, Phys. Rev. Lett. 86, 2529 (2001).

• R.S. Towell et al., Improved Measurement of the d-bar/u-bar Asymmetry in the Nucleon Sea, Phys. Rev. D64, 052002 (2001). [104]

• T.H. Chang et al., J/ polarization in 800-GeV p Cu interactions, Phys. Rev. Lett. 91 211801 (2003).

• L.Y. Zhu et al., Measurement of Angular Distributions of Drell-Yan Dimuons in p + d Interaction at 800-GeV/c, Submitted to Phys. Rev. Lett. arxiv:hep-ex/0609005.

E789 Publications:

• M.S. Kowitt et al., Production of J/ at Large xF in 800 GeV/c p-Copper and p-Beryllium Collisions, Phys. Rev. Lett. 72, 1318 (1994).

• M.J. Leitch et al., Nuclear Dependence of Neutral D Production by 800 GeV/c Protons, Phys. Rev. Lett. 72, 2542 (1994).

• C.S. Mishra et al., Search for the decay D0->+-, Phys. Rev. D50, 9 (1994).

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Publications of the Fermilab Dimuon ProgramE789 Publications (Cont.):

• D.M. Jansen et al., Measurement of the Bottom-Quark Production Cross Section in 800 GeV/c Proton-Gold Collisions, Phys. Rev. Lett. 74, 3118 (1995). [76]

• M.H. Schub et al., Measurement of J/ and 0 Production in 800 GeV/c Proton-Gold Collisions, Phys. Rev. D52, 1307 (1995); Phys. Rev. D53, 570 (1996). [104]

• M.J. Leitch et al., Nuclear Dependence of J/ Production by 800 GeV/c Protons near xF = 0, Phys. Rev. D52, 4251 (1995).

• C.N. Brown et al., Nuclear Dependence of Single-Hadron and Dihadron Production in p-A Interactions at sqrt s = 38.8 GeV, Phys. Rev. C54, 3195 (1996).

• D. Pripstein et al., Search for flavor-changing neutral currents and lepton-family-number violation in two-body D0 decays, Phys. Rev. D61, 032005 (2000).

E772 Publications:

• D.M. Alde et al., Nuclear Dependence of Dimuon Production at 800 GeV, Phys. Rev. Lett. 64, 2479 (1990). [290]

• D.M. Alde et al., A Dependence of J/ and 0 Production at 800 GeV/c, Phys. Rev. Lett. 66, 133 (1991). [259]

• D.M. Alde et al., Nuclear Dependence of the Production of Upsilon Resonances at 800 GeV, Phys. Rev. Lett. 66, 2285 (1991). [144]

• P.L. McGaughey et al., Cross sections for the production of high-mass muon pairs from 800 GeV proton bombardment of 2H, Phys. Rev. D50, 3038 (1994).

• P.L. McGaughey et al., Limit on the d-bar/u-bar asymmetry of the nucleon sea from Drell-Yan production, Phys. Rev. Lett. 69, 1726 (1992).

The three most cited papers have a total of 764 citations

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Deep-Inelastic Scattering versus Drell-Yan

Drell-Yan cross sections are well described by NLO calculations

DIS Drell-Yan

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/ flavor asymmetry from Drell-Yand u

2 2

1Drell-Yan: / 2 (1 ( ) / ( ))

2pd pp d x u x

2 2

21 2 1 2

1 2 1 2. .

4( ) ( ) ( ) ( )

9 a a a a aaD Y

de q x q x q x q x

dx dx sx x

1 2 :at x x

pertubative , should give symmetric ,g uu g dd u d

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Models for asymmetry /d uMeson Cloud Models Chiral-Quark Soliton Model Instantons

• nucleon = chiral soliton

• expand in 1/Nc

• Quark degrees of freedom in a pion mean-field

Theses models also have implications on

• asymmetry between and ( )s x ( )s x

• flavor structure of the polarized sea

Meson cloud has significant contributions to sea-quark distributions

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/ and at large using 50-GeV proton beamd u u x

1 21 2

1 at fixed ,DYd

x xdx dx s

DY cross section is 16 times larger at 50 GeV than at 800 GeV

2 2

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50-cm long / targets

10 protons per spill (3 s)

60-day runs

assuming 50% efficienc

for each t

y

argets

LH LD

D-Y at 50GeV also

directly measure at large

p p

u x

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Modification of Parton Distributions in Nuclei

F2F

e / F

2D

X

EMC effect observed in DIS

How are the antiquark distributions modified in nuclei?

F2 contains contributions from quarks and antiquarks

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Modification of Antiquark Distributions in Nuclei

Nuclear dependence of Drell-Yan

Sensitive to distribution in nucleiu

2

12

2

10 protons per spill (3 s)

10gm/cm t

60-day runs for each targe

arget

a

50-cm long tar

ssuming 50% eff

g

i

e

cien

ts

c

t

y

L

W

D

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Quark Bremsstrahlung in Nuclear Medium• Landau-Pomeranchuk-Migdal (LPM) effect of medium modification for electron bremsstralung has been observed

• LPM effect in QCD remains to be identified

• Quark energy loss ΔE is predicted to be proportional to L2, where L is the length of the medium

• Enhanced quark energy loss in traversing quark-gluon plasma

PHENIX Collaboration

(nucl-ex/0306021)

Quark energy loss in cold nuclei needs to be better measured

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Quark Energy Loss in Cold Nuclei

Semi-inclusive DIS Drell-Yan

(PRL 89 (2002) 162301) (PRL 86 (2001) 4483)

0.5 GeV/fmdE

dx 2.5 0.6 GeV/fm

dE

dx

5<M<6 GeV

7<M<8 GeV

(depends on shadowing correction)

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Quark Energy Loss with D-Y at 50 GeV

Fractional energy loss is larger at 50 GeV

Possible to test the predicted L2-dependence from the A-dependence measurement

Garvey and Peng, PRL 90 (2003) 092302

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PAC report on P04 (July 2006)• “… This experiment will exploit the unique opportunity to study

the sea quark distribution at the 50 GeV J-PARC accelerator. The PAC recognizes the physics potential and expects that interesting results will come from the experiment.”

• “... The cost and schedule of the experiment at J-PARC strongly depends on the situation of the Fermilab (E906) experiment.”

• “… the physics case is stronger for the primary beam energy at 50 GeV, whose timescale is uncertain. The proponents presented an option to study J/Ψ production at 30 GeV. The PAC considers that this measurement is also interesting, but feels that the experiment is less justified when the study of J/Ψ production becomes the primary purpose.”

• “… Thus the PAC leaves this experiment in a deferred status.”

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Status of Fermilab E906• Approved by Fermilab PAC in 2001

• Reviewed by Fermilab PAC again in October 2006, and the PAC again endorsed E906

• A technical review of E906 was held at Argonne National Lab in December 2006

• In June 2007, US DOE/Office of Nuclear Physics decided to fund E906– Construction of the coils for a new magnet

– Construction/refurbishing the hodoscopes and tracking chambers

– Construction and installation will be completed by Fall of 2009

• E906 is scheduled to run for two years in 2009-2011

• Equipments would become available in late 2011

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Dimuon measurements at 30 GeV

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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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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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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Determination of / Asymmetry

via / Production at 30 GeV

d u

J

( / ) / ( / ) is sensitive to /p d J p up dJ

u d

d u

(A unique feature at 30-50 GeV)

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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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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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High intensity polarized H- source(at RHIC)

KEK OPPISupgraded at TRIUMF

80 - 85 % Polarization

151011 protons/pulse at source

61011 protons/pulse at end of LINAC

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25 % AGS super-conducting helical snake

Warm helical partial Siberian snake

Funded by RIKEN, built by Takano Ind.

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Study of proton spin at J-PARC • Origin of the nucleon spin 1/2 ?

– polarized DIS experiments showed the quark-spin contribution is only 10-30%– gluon-spin contribution ?

• Semi-inclusive SID at DESY and CERN• polarized p-p collision at BNL/RHIC

• will be concluded in the near future

– orbital angular momentum ?• measurements should be developed for the final solution

Lg 2

1

2

1

- excludes maximal g scenario- conclusively consistent with std g and g=0

Small Δg implies significant contribution from L

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Single-spin asymmetry in polarized p-p collision• Orbital angular momentum

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

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

• Why Drell-Yan?– A simple process in hadron reactions

– No final-state effect → no Collins effect

• Why J-PARC?– Polarized beam feasible

– High luminosity (L=2x1036/cm 2/sec)

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2

( ) ( )

( ) ( )

q T q q qqDYN

q q q q qq

e f x f xA

e f x f x

(See talks by Yuji Goto)

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Spin physics with dimuons at J-PARC

Drell-Yan AN (Ji et al.)-sensitive to Sivers effect at low qT << Q-sensitive to higher-twist effect at high qT ~ Q-Sivers function in Drell-Yan is expected to have a sign opposite to that in DIS.

Single-spin asymmetry (AN) measurements for orbital angular momentum– Drell-Yan, J/Ψ

– Open-geometry apparatus: D-meson, χc, etc.

Other measurements– Drell-Yan ALL for sea-quark polarization

– Drell-Yan ATT for transversity

– Unpolarized Drell-Yan for Boer-Mulders function

– ALL for J/Ψ for gluon polarization

D-Y ALL at 50 GeV

GRSV

G-S

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High momentum beamline• Not day-1, but expected around 2011.• Primary protons and high momentum secondary beams.• Issue:

– Development of equipments at the separation point.

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• Two vertically bending magnets with PT kick of 2.47 GeV/c and 0.5 GeV/c

• A tappered copper beam dump and Cu/C absorbers in the first magnet

• Tracking is provided by three stations of MWPCs and drift chambers

• Station 4 provides muon identification and tracking

• 2 x 1012 50 GeV protons/spill is requested

Schematics of the spectrometer

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Apparatus

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M1 Magnet

• New coils• Reuse whole pieces of SM12 magnet

yoke (SM12 was the 14.4 m dipole used by E866)

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Proposed Time Line 2007 2008 2009 2010 2011 2012 2013 2014

E906 Preparation

E906 Beam

E906 Decommissioning, transfer to J-PARC

J-PARC Exp Preparation

High Mom Beamline Availability (according to Prof. Takasaki’s slide)

J-PARC Exp Beam

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Summary• We propose to study high-mass dimuon production at

J-PARC with a high-rate spectrometer.• A rich physics program in Drell-Yan and J/Ψ

production can be pursued at J-PARC.• Fermilab E906 apparatus could be reused at J-PARC in

a cost-effective and efficient manner. • J/Ψ production at 30 GeV could provide very

interesting new data. It could be dominated by quark-antiquark annihilation similar to Drell-Yan.

• An extensive program in spin physics can be pursued using this spectrometer together with polarized beam/target in the future.

• A stage-1 approval for P04 is requested. It is crucial for the preparation of the experiment.