1 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)

2 Collaboration The Institutions Abilene Christian University 1, Argonne National Laboratory 2, Duke University 3, High Energy Accelerator Research Organization 4, University of Illinois at Urbana-Champaign 5, Los Alamos National Laboratory 6, Pusan National University 7, RIKEN 8, Seoul National University 9, Tokyo Institute of Technology 10, Tokyo University of Science 11, Yamagata University 12 J.K. Ahn 7, J. Chiba 11, Seonho Choi 9, D. Dutta 3, Y. Fukao 8, H. Gao 3, Y. Goto 8, M. Grosse-Perdekamp 5, L.D. Isenhower 1, T. Iwata 12, S. Kato 10, S. Kumano 4, M.J. Leitch 6, M.X. Liu 6, P.L. McGaughey 6, J.C. Peng 5, P. Reimer 2, M. Sadler 1, N. Saito 4, S. Sawada 4, R. Seidl 5, T.-A. Shibata 10, A. Taketani 8, K.H. Tanaka 4, M. Togawa 8, R. Towell 1, H.Y. Yoshida 12 Collaboration members New collaborators are underlined

3 Physics with High-Mass Dimuons at J-PARC

4 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, Υ FNAL E866

5 Publications of the Fermilab Dimuon Program E866/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, (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, (2001). [104] T.H. Chang et al., J/  polarization in 800-GeV p Cu interactions, Phys. Rev. Lett (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/ E789 Publications: M.S. Kowitt et al., Production of J/  at Large x F 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 D 0 ->  +  -, Phys. Rev. D50, 9 (1994).

6 Publications of the Fermilab Dimuon Program E789 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 x F = 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 D 0 decays, Phys. Rev. D61, (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 2 H, 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

7 Deep-Inelastic Scattering versus Drell-Yan Drell-Yan cross sections are well described by NLO calculations DIS Drell-Yan

8

9 Models for asymmetry Meson Cloud ModelsChiral-Quark Soliton ModelInstantons 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 flavor structure of the polarized sea Meson cloud has significant contributions to sea-quark distributions

10

11 Modification of Parton Distributions in Nuclei F 2 Fe / F 2 D X EMC effect observed in DIS How are the antiquark distributions modified in nuclei? F 2 contains contributions from quarks and antiquarks

12 Modification of Antiquark Distributions in Nuclei Nuclear dependence of Drell-Yan

13 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 L 2, where L is the length of the medium Enhanced quark energy loss in traversing quark-gluon plasma PHENIX Collaboration (nucl-ex/ ) Quark energy loss in cold nuclei needs to be better measured

14 Quark Energy Loss in Cold Nuclei Semi-inclusive DIS Drell-Yan (PRL 89 (2002) ) (PRL 86 (2001) 4483) 5<M<6 GeV 7<M<8 GeV (depends on shadowing correction)

15 Quark Energy Loss with D-Y at 50 GeV Fractional energy loss is larger at 50 GeV Possible to test the predicted L 2 -dependence from the A- dependence measurement Garvey and Peng, PRL 90 (2003)

16 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.”

17 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 Equipments would become available in late 2011

18 Dimuon measurements at 30 GeV Very few data for J/ Ψ production at GeV Schub et al., Fermilab E789, PR D52 (1995) GeV/c at CERN-PS 70 GeV/c at IHEP

19 J/Ψ Production at 30 GeV At 800 GeV, J/Ψ production is dominated by gluon-gluon fusion At 30 GeV J/Ψ production is dominated by quark-antiquark annihilation J/Ψ production at 30 GeV is sensitive to quark and antiquark distributions

20 Expected J/ Ψ yields and kinematic coverage J/ Ψ yields for a two-month p+d run at 30 GeV protons/spill 50-cm long liquid deuterium target Assume 50 percent efficiency Expected total number of J/ Ψ events: ~ 8x10 6 Broad coverage in x F, x 1, x 2, p T

21 (A unique feature at GeV)

22 Nuclear Dependence of J/Ψ Production at 30 GeV 30 GeV data would provide an interesting test for the x F -scaling in J/ψ production Very few data exist for negative x F region

23 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 Beam Polarimeter 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 GeV 50 GeV

24 High intensity polarized H - source (at RHIC) KEK OPPIS upgraded at TRIUMF % Polarization 15  protons/pulse at source 6  protons/pulse at end of LINAC

25 25 % AGS super-conducting helical snake Warm helical partial Siberian snake Funded by RIKEN, built by Takano Ind.

26 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 - excludes maximal  g scenario - conclusively consistent with std  g and  g=0 Small Δg implies significant contribution from L

27 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 E lab = 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=2 x10 36 /cm 2 /sec) (See talks by Yuji Goto)

28 Spin physics with dimuons at J-PARC Drell-Yan A N (Ji et al.) -sensitive to Sivers effect at low q T << Q -sensitive to higher-twist effect at high q T ~ Q -Sivers function in Drell-Yan is expected to have a sign opposite to that in DIS. Single-spin asymmetry (A N ) measurements for orbital angular momentum –Drell-Yan, J/Ψ –Open-geometry apparatus: D-meson, χ c, etc. Other measurements –Drell-Yan A LL for sea-quark polarization –Drell-Yan A TT for transversity –Unpolarized Drell-Yan for Boer-Mulders function –A LL for J/Ψ for gluon polarization D-Y A LL at 50 GeV GRSV G-S

29 High momentum beamline Not day-1, but expected around Primary protons and high momentum secondary beams. Issue: –Development of equipments at the separation point.

30 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 GeV protons/spill is requested Schematics of the spectrometer

31 Apparatus

32 M1 Magnet New coils Reuse whole pieces of SM12 magnet yoke (SM12 was the 14.4 m dipole used by E866)

33 Proposed Time Line 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

34 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.