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Dimuon Production with High Energy Proton Beams

Dimuon Production with High Energy Proton Beams. Jen-Chieh Peng, University of Illinois. Highlights of results from Fermilab E772, E789 and E866 dimuon experiments What have we learned? Future prospects of Fermilab E906 and J-PARC dimuon experiments What do we hope to learn?.

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Dimuon Production with High Energy Proton Beams

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  1. Dimuon Production with High Energy Proton Beams Jen-Chieh Peng, University of Illinois • Highlights of results from Fermilab E772, E789 and E866 dimuon experiments • What have we learned? • Future prospects of Fermilab E906 and J-PARC dimuon experiments • What do we hope to learn? KEK, Jan. 11, 2008

  2. A Brief History

  3. First Dimuon Experiment Lederman et al. PRL 25 (1970) 1523 Experiment originally designed to search for neutral weak boson (Z0) Miss the J/Ψ signal !

  4. Lepton-pair production is a powerful tool for finding new quarks/particles

  5. Lepton-pair production also provides unique information on parton distributions Probe antiquark in nucleon Probe antiquark in pion Probe antiquark in antiproton

  6. (E605/772/789/866) Meson East Spectrometer Open-aperture Closed-aperture Beam-dump (Cu) J/Ψ J/Ψ Ψ’ σ(J/ψ) ~ 15 MeV σ(J/ψ) ~ 150 MeV σ(J/ψ) ~ 300 MeV

  7. Physics with High-Mass Dimuons

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

  9. Modification of Parton Distributions in Nuclei EMC effect observed in DIS F2Fe / F2D X F2 contains contributions from quarks and antiquarks How are the antiquark distributions modified in nuclei?

  10. The Drell-Yan Process: The x-dependence of can be directly measured

  11. PRL 83 (1999) 2304 The Drell-Yan p-A measurement can be extended to lower x at RHIC

  12. Is in the proton? = Test of the Gottfried Sum Rule New Muon Collaboration (NMC) obtains SG = 0.235 ± 0.026 ( Significantly lower than 1/3 ! )

  13. The Drell-Yan Process: The x-dependence of can be directly measured

  14. Fermilab E866 Measurements

  15. Fermilab E866 Measurements To appear in PRL, arXiv: 0710.2344

  16. Models for asymmetry Meson Cloud Models Chiral-Quark Soliton Model Instantons Quark degrees of freedom in a pion mean-field nucleon = chiral soliton expand in 1/Nc Theses models also have implications on • asymmetry between and flavor structure of the polarized sea

  17. Spin and flavor are closely connected Meson Cloud Model Pauli Blocking Model A spin-up valence quark would inhibit the probability of generating a spin-down antiquark Instanton Model Chiral-Quark Soliton Model Statistical Model

  18. JCP, Eur. Phys. J. A18 (2003) 395

  19. 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

  20. Quark Energy Loss in Cold Nuclei Drell-Yan Semi-inclusive DIS (PRL 86 (2001) 4483) (PRL 89 (2002) 162301) 5<M<6 GeV 7<M<8 GeV (depends on shadowing correction)

  21. Quark Energy Loss with D-Y at Lower Energies Correspond to larger x2, no nuclear shadowing Fractional energy loss is larger at 50 GeV Possible to test the LPM effect from the A-dependence Garvey and Peng, PRL 90 (2003) 092302 Fermilab E906 can study this at 120 GeV

  22. Drell-Yan decay angular distributions Θ and Φ are the decay polar and azimuthal angles of the μ+ in the dilepton rest-frame Collins-Soper frame A general expression for Drell-Yan decay angular distributions: In general :

  23. Decay Angular Distribution of Drell-Yan Data from Fermilab E772 McGaughey, Moss, Peng; Annu. Rev. Nucl. Part. Sci. 49 (1999) 217 (hep/ph-9905409)

  24. Drell-Yan decay angular distributions Θ and Φ are the decay polar and azimuthal angles of the μ+ in the dilepton rest-frame Collins-Soper frame A general expression for Drell-Yan decay angular distributions:

  25. Decay angular distributions in pion-induced Drell-Yan NA10 π- +W Z. Phys. 37 (1988) 545 Dashed curves are from pQCD calculations

  26. Decay angular distributions in pion-induced Drell-Yan Is the Lam-Tung relation violated? 140 GeV/c 194 GeV/c 286 GeV/c Data from NA10 (Z. Phys. 37 (1988) 545)

  27. QCD vacuum effects Brandenburg, Nachtmann & Mirkes, Z. Phy. C60,697(1993) • Nontrivial QCD vacuum may lead to correlation between the transverse spins of the quark (in nucleon) and the antiquark (in pion). • The helicity flip in the instanton-induced contribution may lead to nontrivial vacuum. Boer,Brandenburg,Nachtmann&Utermann, EPC40,55(2005). 0=0.17, mT=1.5

  28. Boer-Mulders function h1┴ 1=0.47, MC=2.3 GeV Boer, PRD 60 (1999) 014012

  29. Motivation for measuring decay angular distributions in p+p and p+d Drell-Yan • No proton-induced Drell-Yan azimuthal decay angular distribution data • Provide constraints on models explaining the pion-induced Drell-Yan data. (h1┴ is expected to be small for sea quarks. The vacuum effects should be similar for p+N and π+N) • Test of the Lam-Tung relation in proton-induced Drell-Yan • Compare the decay angular distribution of p+p versus p+d

  30. Decay angular distributions for p+d Drell-Yan at 800 GeV/c p+d at 800 GeV/c No significant azimuthal asymmetry in p+d Drell-Yan!

  31. Azimuthal cos2Φ Distribution in p+d Drell-Yan L.Y. Zhu,J.C. Peng, P. Reimer et al., PRL 99 (2007) 082301 With Boer-Mulders function h1┴: ν(π-Wµ+µ-X)~ valence h1┴(π) * valence h1┴(p) ν(pdµ+µ-X)~ valence h1┴(p) * sea h1┴(p)

  32. What does this mean? • These results suggest that the Boer-Mulders functions h1┴ for sea quarks are significantly smaller than for valence quarks. • These results also suggest that the non-trivial vacuum correlation between the sea-quark transverse spin (in one hadron) and the valence-quark transverse spin (in another hadron) is small.

  33. J/Ψ and Ψ’ cross sections E789 data p + Au → J/Ψ (Ψ’) + x (open aperture) S1/2 = 38.8 GeV Large discrepancy between the observed J/Ψ (Ψ’) cross sections and the calculations of color-singlet model

  34. Polarization of J/Ψ E866 p + Cu → J/Ψ + x (beam dump) s1/2 = 38.8 GeV (hep-ex/030801, T. Chang et al.) Typical dimuon mass spectrum for various xF, pT, cosθ bins dσ/dΩ ~ 1 + λcos2θ (extraction of λ for various xF, pT bins)

  35. 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 λ is small, but nonzero λ becomes negative at large xF No strong pT dependence for λ hep-ex/030801 Polarization of Ψ’ is being analyzed

  36. Polarization of Υ(1S),Υ(2S+3S) p + Cu →Υ + x (E866 beam-dump data) Dimuon mass spectrum Decay angular distributions Υ(1S) Υ(2S+3S) Brown et al. PRL 86, 2529 (2001)

  37. 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! λ pT (GeV) λ xF Brown et al. PRL 86, 2529 (2001)

  38. Nuclear effects of Quarkonium productions p + A at s1/2 = 38.8 GeV E772 data σ(p+A) = Aασ(p+N) Strong xF - dependence Nuclear effects scale with xF, not x2 What about negative xF?

  39. PT - broadening for D-Y, J/Ψ and Υ Extract <PT2> from fits to data Δ<PT2> for J/Ψ is larger than for D-Y Similar behavior for J/Ψ and Υ

  40. Comparison between the J/Ψ and Ψ’ nuclear effects p + A → J/Ψ or Ψ’ at s1/2 = 38.8 GeV α(xF) is largely the same for J/Ψ and Ψ’ (except at xF ~ 0 region) ‘Universal’ behavior for α(pT) (similar for J/Ψ, Ψ’; weak s1/2 dependence)

  41. Nuclear effects of open-charm production p + A → D + x at s1/2 = 38.8 GeV E789 open-aperture, silicon vertex + dihadron detection h+h- mass spectrum (after vertex cut) No nuclear effect for D production (at xF ~ 0) D0→ K-π+ Need to extend the measurements to large xF region

  42. hep-ex/0506071

  43. Fermilab E906/Drell-Yan Collaboration Abilene Christian University Donald Isenhower, Mike Sadler, Rusty Towell Argonne National Laboratory John Arrington, Don Geesaman*, Kawtar Hafidi, Roy Holt, Harold Jackson, David Potterveld Paul E. Reimer*, Patricia Solvignon University of Colorado Ed Kinney Fermi National Accelerator Laboratory Chuck Brown University of Illinois Naiomi C.R Makins, Jen-Chieh Peng Los Alamos National Laboratory Gerry Garvey, Mike Leitch, Pat McGaughey, Joel Moss *Co-Spokespersons University of Maryland Elizabeth Beise Rutgers University Ron Gilman, Charles Glashausser, Xiaodong Jaing, E. Kuchina, Ron Ransome, Elaine Schulte Texas A & M University Carl Gagliardi, Bob Tribble Thomas Jefferson National Accelerator Facility Dave Gaskell Valparaiso University Don Koetke, Jason Webb Academia Sinica Wen-Chen Chang, Yen-Chu Chen, Ping-Kun Teng

  44. Fermilab Accelerator Complex:Fixed Target Program Fixed Target Beamlines Tevatron 800 GeV Main Injector 120 GeV

  45. Measurement of High-Mass dimuon Production at J-PARC (P-04) Collaboration Abilene Christian University, Argonne National Laboratory, Duke University, High Energy Accelerator Research Organization, University of Illinois at Urbana-Champaign, Kyoto University, Los Alamos National Laboratory, Pusan National University, RIKEN, Seoul National University, Tokyo Institute of Technology, Tokyo University of Science, Yamagata University Collaboration members J.K. Ahn, J. Chiba, Seonho Choi, D. Dutta, H. Gao, Y. Goto, L.D. Isenhower, T. Iwata, S. Kato,M.J. Leitch, M.X. Liu, P.L. McGaughey, J.C. Peng, P. Reimer, M. Sadler, N. Saito, S. Sawada,T.-A. Shibata, K.H. Tanaka, R. Towell, H.Y. Yoshida (Spokesperson: S. Sawada and J. C. Peng)

  46. Polarized proton beam at J-PARC ? • 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 pC CNI Polarimeter Extracted Beam Polarimeter Pol. H- Source Rf Dipole 180/400 MeV Polarimeter 25-30% Helical Partial Siberian Snakes

  47. Physics with High-Mass Dimuons at J-PARC

  48. Summary • Dimuon production experiments at Fermilab have provided unique information on nucleon and nuclear substructures • Future dimuon production experiments at lower beam energies (120 GeV Main-Injector and 50 GeV J-PARC) could provide interesting new information at large x and spin-dependent parton distributions in the nucleons

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