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Unpolarized Drell-Yan Experiments at Fermilab and J-PARC

Unpolarized Drell-Yan Experiments at Fermilab and J-PARC. What do we measure with Drell-Yan? Selectivity for sea quarks What Physics can we address? Dbar/ubar Nuclear modifications Large-x structure Parton energy loss QCD—Lam Tung Relation Meson Structure (Seonho Choi, NP08)

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Unpolarized Drell-Yan Experiments at Fermilab and J-PARC

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  1. Unpolarized Drell-Yan Experiments at Fermilab and J-PARC • What do we measure with Drell-Yan? • Selectivity for sea quarks • What Physics can we address? • Dbar/ubar • Nuclear modifications • Large-x structure • Parton energy loss • QCD—Lam Tung Relation • Meson Structure (Seonho Choi, NP08) • Polarized Structure (Yuji Goto here, NP’08) • How and Where? Paul E. Reimer 7 April 2008 Goal: Present an overview of Drell-Yan physics at J-PARC and Fermilab

  2. xtarget xbeam Drell-Yan scattering: A laboratory for sea quarks Detector acceptance chooses xtarget and xbeam. • Fixed target ) high xF = xbeam – xtarget • Valence Beam quarks at high-x. • Sea Target quarks at low/intermediate-x. E906 Spect. Monte Carlo Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN

  3. Main Injector 120 GeV Fixed Target Beam lines Tevatron 800 GeV Advantages of 120 GeV Main Injector The Future Fermilab E906 • Data in 2009 • 1H, 2H, and nucl. targets • 120 GeV proton Beam The (very successful) past: Fermilab E866/NuSea • Data in 1996-1997 • 1H, 2H, and nucl. targets • 800 GeV proton beam J-PARC • Polarized beams and targets • Meson beams • 50 GeV proton Beam • Cross section scales as 1/s • Backgrounds, (J/ and charm decays) scale as s Within limits Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN

  4. " # r 2 M 1 2 4 ± + + x x x = F F 1 2 2 ; s • Reconstruct M2, pT, p|| • M2 = x1x2s, • xF = 2p||/s1/2≈ x1 – x2 Fermilab E866 Detector • Target-to-dump distance important • Acceptance • Background from § decay (especially at 50 GeV) • Target/Dump Separation • Fringe Field (polarized target) Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN

  5. What is the distribution of sea quarks? In the nucleon: • Sea and gluons are important: • 98% of mass; 60% of momentum at Q2 = 2 GeV2 • Not just three valence quarks and QCD. Shown by E866/NuSea d-bar/u-bar data • What are the origins of the sea? • Significant part of LHC beam. CTEQ6m In nuclei: • The nucleus is not just protons and neutrons • What is the difference? • Bound system • Virtual mesons affects antiquarks distributions Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN

  6. Light Antiquark Flavor Asymmetry: Brief History • Naïve Assumption: • NMC (Gottfried Sum Rule) • NA51 (Drell-Yan) • E866/NuSea (Drell-Yan) • Knowledge of distributions is data driven • Sea quark distributions are difficult for Lattice QCD Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN

  7. · ¸ 3 3 a a h j i ( ) h j i h j i h j i h j i h j i h j i b b P P P P N N ¢ ¢ 1 1 ¡ ¡ + + ¡ + q q a q q a ¼ q ¼ ¼ q ¼ ¼ ¼ 3 = = 0 0 0 0 0 0 ¹ ¹ ¹ ¹ 1 ( ) ( ) ( ) ( ) 1 : : : d d ¢ ¢ 2 2 d d d d L ¡ ¡ b ¹ ¹ Z Z ¹ 2 5 2 0 + 1 1 ¹ ¹ ¼ ¡ ( ) ( ) [ ( ) ( ) ] x u x u x x d d ¢ ¢ / u u u u a Z Z ¡ ¡ ¹ 2 5 R L R L L R L R p x u x u x x £ ¤ ¹ = a I I I I ( ) ( ) [ ] d b d d b ¢ ¢ 0 1 0 0 2 2 2 1 5 ¡ ¡ ¡ ¹ £ ¤ • Chiral Quark models—effective Lagrangians ¹ ( ) ( ) [ ] x u x a g u x a d d d 5 ¢ ¢ = = ! = = = = ! 0 1 0 0 1 4 3 1 4 3 A ¡ ¡ ¹ x u x a g u x a : : : = = ! = = = ! A 3 3 2 7 : : : 3 3 0 0 0 0 • Instantons • Statistical Parton Distributions Models Relate Antiquark Flavor Asymmetry and Spin • Meson Cloud in the nucleon—Sullivan process in DIS Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN

  8. Something is missing • All non-perturbative models predict large asymmetries at high x. • Are there more gluons and therefore symmetric anti-quarks at higher x? • Does some mechanism like instantons have an unexpected x dependence? (What is the expected x dependence for instantons in the first place?) Perturbative sea apparently dilutes meson cloud effects at large-x Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN

  9. d ¹ ¯ · ¸ d p 1 ¾ ¯ 1 + ¼ ¯ 2 2 p p ¹ ¾ u ¯ 0 > > x F Extracting d-bar/-ubar From Drell-Yan Scattering • Sensitivity to d-bar/u-bar depends on kinematics • Need high xF for extraction Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN

  10. Drell-Yan Absolute Cross Sections • ¼ of data represented in plot (alternate decades, alternate targets) • Last few xF bins show PDF’s “over predict” NLO cross section Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN

  11. Drell-Yan Absolute Cross Sections: xtarget • Reach high-x through beam proton Large xF) large xbeam. • High-x distributions poorly understood • Nuclear corrections are large, even for deuterium • Lack of proton data • Proton-Proton • no nuclear corrections • 4u(x) + d(x) • Data are free for analysis after dbar/ubar expt. • Both J-PARC and Fermilab will have similar reach in statistics and in xTarget. Preliminary Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN

  12. Alde et al (Fermilab E772) Phys. Rev. Lett. 64 2479 (1990) Structure of nucleonic matter: How do sea quark distributions differ in a nucleus? • Intermediate-xsea PDF’s absolute magnitude set by -DIS on iron. • Are nuclear effects the same for the sea as for valence? • Are nuclear effects with the weak interaction the same as electromagnetic? • EMC: Parton distributions of bound and free nucleons are different. • Antishadowing not seen in Drell-Yan—Valence only effect • What can the sea parton distributions tell us about the effects of nuclear binding? Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN

  13. Structure of nucleonic matter: Where are the nuclear pions? • The binding of nucleons in a nucleus is expected to be governed by the exchange of virtual “Nuclear” mesons. • No antiquark enhancement seen in Drell-Yan (Fermilab E772) data. • Contemporary models predict large effects to antiquark distributions as x increases. • Models must explain both DIS-EMC effect and Drell-Yan Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN

  14. = 2 3 A p T P ¼ i m n x 1 Nuclear Antiquark Sea measured at J-PARC • J-PARC can extend reach to significantly higher x • First test QCD Factorization at low energy--must be valid. Bodwin, Brodsky and LePage PRD 39, 3287 (1989). • Study higher-twist effects • Extend reach to higher x Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN

  15. X1 Partonic Energy Loss • An understanding of partonic energy loss in both cold and hot nuclear matter is paramount to elucidating RHIC data. • Pre-interaction parton moves through cold nuclear matter and looses energy. • Apparent (reconstructed) kinematic values (x1 or xF) is shifted • Fit shift in x1 relative to deuterium • Models: • Galvin and Milana • Brodsky and Hoyer • Baier et al. X1 Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN

  16. Partonic Energy Loss E866/NuSea • E866 data are consistent with NO partonic energy loss for all three models • Caveat: A correction must be made for shadowing because of x1—x2 correlations • E866 used an empirical correction based on EKS fit do DIS and Drell-Yan. • Treatment of parton propagation length and shadowing are critical • Johnson et al. find 2.7 GeV/fm (≈1.7 GeV/fm after QCD vacuum effects) • Same data with different shadowing correction and propagation length • Better data outside of shadowing region are necessary. Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN

  17. E906 uncertainties Shadowing region removed Parton Energy Loss • Shift in x / 1/s • Larger at 120 GeV; Even larger at 50 GeV • Sufficient statistics to cut shadowing region, x2 < 0.1, from data. Energy loss upper limits based on E866 Drell-Yan measurement J-PARC 50 GeV Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN

  18. Meson Drell-Yan(Seonho Choi, Seoul, NP08) • High-x  parton distributions • High-x from of (1-x) • Predictions for  from Dyson-Schwinger, pQCD and Nambu-Jona-Lasinio models • Data fall predictions, but poor x resolution • Charge symmetry violation +/- on deuterium target • Difficulty producing pure + beam • Kaon Parton Distributions • Need 50 GeV beam for reasonable meson energy (my opinion) • Low secondary beam flux • Dump and magnet possibly not necessary (Needs simulation) • Increase acceptance by moving spectrometer forward • J-PARC only Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN

  19. d ¾ 2 ¸ µ 1 + / c o s d ­ µ Á i 2 + ¹ s n c o s ¸ 1 2 ¡ º = º 2 µ Á i 2 + s n c o s 2 Generalized Angular Distributions Chi-Sing Lam and Wu-Ki Tung—basic formula for lepton pair production angular distributions PRD 18 2447 (1978) Helped to validate the Drell-Yan picture of quark-antiquark annihilation for lepton pair production • Lam-Tung Relation Direct analogy to the Callan-Gross relation in DIS Normally written as Robust Prediction of QCD • Unaffected by O(s) (NLO) corrections • NNLO [O(s2)] corrections also small Mirkes and Ohnemus, PRD 51 4891 (1995) • Also holds under resummation Berger, Qiu, Rodriguez-Pedraza, PRD 76, 074006 (2007) Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN

  20. Lam-Tung Relation • - Drell-Yan • Violates L-T relation • Large (cos2) dependence • Strong with pT • Proton Drell-Yan • Consistent with L-T relation • No (cos2) dependence • No pT dependence • Boer-Mulders function h1?: • ( W!+-X) Valence h1?() £valence h1?(p) • (pd!+-X) Valence h1?(p) £sea h1?(p) • J-PARC—both w/same Spectrometer • Alternative: Higher twist √s dependence—need J-PARC test Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN

  21. Transversely Polarized Target or beam Sivers’ distribution f?1T(x, kT) • Single spin asymmetry • Possibly explanation for E704 data • Collins Fragmentation function could also produce such an asymmetry Fermilab E704, Phys. Rev. Lett. 77, 2626 (1996) See talk by Dr. Yuji Goto • HERMES has observed both effects in SIDIS • With Drell-Yan: f?1T(x, kT)|DIS = -f?1T(x, kT)|D-Y • With transversely polarized target one measures sea quarks • Sea quark effects might be small J-PARC ONLY Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN

  22. J-PARC Experiment Runs Expt. Funded Magnet Design Experiment And construction Construction Proposed Jan. 2007 Publications 2012 2009 2008 2011 2010 Drell-Yan timeline • Fermilab PAC approved the experiment in 2001, but experiment was not scheduled due to concerns about “proton economics” • Spectrometer upgrade funded by DOE/Office of Nuclear Physics (already received $538k in FY07) • Fermilab PAC reaffirms earlier decision in Fall 2006 • Scheduled to run in 2010 for 2 years of data collection • Apparatus available for future program at J-PARC • Significant interest from collaboration for continued program here Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN

  23. Drell-Yan at Fermilab and J-PARC • d-bar/u-bar • Fermilab and extended range from J-PARC 50 GeV • The origins of the sea quarks? • The high-x structure of the proton? • Antiquarks in Nuclei • Do colored partons lose energy in cold nuclear matter? • Meson Drell-Yan (J-PARC) • Polarized Drell-Yan (J-PARC) Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN

  24. Additional Material Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN

  25. FNAL E866/NuSea Collaboration Louisiana State University Paul Kirk, Ying-Chao Wang, Zhi-Fu Wang New Mexico State University Mike Beddo, Ting Chang, Gary Kyle, Vassilios Papavassiliou, J. Seldon, Jason Webb Oak Ridge National Laboratory Terry Awes, Paul Stankus, Glenn Young Texas A & M University Carl Gagliardi, Bob Tribble, Eric Hawker, Maxim Vasiliev Valparaiso University Don Koetke, Paul Nord Abilene Christian University Donald Isenhower, Mike Sadler, Rusty Towell, Josh Bush, Josh Willis, Derek Wise Argonne National Laboratory Don Geesaman, Sheldon Kaufman, Naomi Makins, Bryon Mueller, Paul E. Reimer Fermi National Accelerator Laboratory Chuck Brown, Bill Cooper Georgia State University Gus Petitt, Xiao-chun He, Bill Lee Illinois Institute of Technology Dan Kaplan Los Alamos National Laboratory Melynda Brooks, Tom Carey, Gerry Garvey, Dave Lee, Mike Leitch, Pat McGaughey, Joel Moss, Brent Park, Jen-Chieh Peng, Andrea Palounek, Walt Sondheim, Neil Thompson Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN

  26. Fermilab E906/Drell-Yan Collaboration Abilene Christian University Donald Isenhower, Mike Sadler, Rusty Towell Academia Sinica Wen-Chen Chang, Yen-Chu Chen, Da-Shung Su 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 Naomi C.R Makins, Jen-Chieh Peng *Co-Spokespersons Ling-Tung University Ting-Hua Chang Los Alamos National Laboratory Gerry Garvey, Mike Leitch, Pat McGaughey, Joel Moss Maryland Betsy Beise Rutgers University Ron Gilman, Charles Glashausser, Xiaodong Jaing, Elena Kuchina, Ron Ransome, Elaine Schulte Texas A & M University Carl Gagliardi, Robert Tribble Thomas Jefferson National Accelerator Facility Dave Gaskell Valparaiso University Don Koetke, Jason Webb Pending Collaborators RIKEN Yuji Goto, Atsushi Taketani, Yoshinori Fukao, Manabu Togawa Kyoto University KenIchi Imai, Tomo Nagae Tokyo Tech Toshi-Aki Shibata, Yoshiyuki Miyachi KEK Shin'ya Sawada Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN

  27. Collaboration: Measurement of High-Mass Dimuon Production at the 50-GeV Proton Synchrotron Brookhaven National Laboratory M. Bai, H. Huang, A. U. Luccio, T. Roser, A. Zelenski University of Illinois R. Seidl, M. Grosse Perdekamp, J.-C. Peng KEK S. Ishimoto, C. Ohmori, A. Molodojentsev, N. Saito, H. Sato*, S. Sawada, J. Takano Kyoto University K. Imai Los Alamos National Laboratory M. Brooks, X. Jiang, G. Kunde, M. J. Leitch, M. X. Liu, P. L. McGaughey Osaka University K. Hatanaka RIKEN Y. Fukao, Y. Goto*, A. Taketani, M. Togawa Rikkyo University K. Kurita, Tokyo Tech T.-A. Shibata Tokyo University J. Chiba Yamagata University N. Doshita, T. Iwata, K. Kondo Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN

  28. Collaboration: Polarized Proton Acceleration at J-PARC Los Alamos National Laboratory M. J. Leitch, M. X. Liu, P. L. McGaughey RIKEN Y. Goto Tokyo Tech T.-A. Shibata Tokyo University J. Chiba Yamagata University T. Iwata, S. Kato, H. Y. Yoshida Abilene Christian University L. D. Isenhower, M. Sadler, R. Towel Argonne National Laboratory P. E. Reimer Duke University D. Dutta, H. Gao University of Illinois J.-C. Peng* KEK S. Sawada*, K. H. Tanaka Kyoto University N. Saito Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN

  29. Next-to-Leading Order Drell-Yan • Next-to-leading order diagrams complicate the picture • These diagrams are responsible for 50% of the measured cross section • Intrinsic transverse momentum of quarks (although a small effect, l > 0.8) Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN

  30. Kulagin and Petti sea vs. valence nuclear effects Sea Valence Nuclear Physics A 765 (2006) 126–187 Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN

  31. Aside: Rescaling Models in Trouble? • Prediction of  mass/width modification not seen in JLab/CLAS data Nasseripour et al. (CLAS) PRL 99, 262302 (2007) Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN

  32. Proton Valence Structure: Unknown as x! 1 • Theory • Exact SU(6): d/u ! 1/2 • Diquark S=0 dom.: d/u ! 0 • pQCD: d/u ! 3/7 • Data • Binding/Fermi Motion effects in deuterium—choice of treatments. • Proton data is needed. Relative uncertainty up-quark distribution (CTEQ6e) Petratos et al. nucl-ex/0010011 Reality: We don’t even know the u or d quark distributions—there really is very little high-x proton data Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN

  33. Drell-Yan Absolute Cross Sections: xtarget Measures a convolution of beam and target PDF • absolute magnitude of high-x valence beam distributions • absolute magnitude of the sea in the target • Currently determined by –Fe DIS Preliminary Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN

  34. Detector Rates Expected single muon rates per 2£1012 protons from decay-in-flight mesons which pass through the detector ('s) and satisfy trigger matrix tracking requirements (Trks.) from liquid hydrogen and deuterium targets and the copper beam dump. Paul E. Reimer--J-PARC Meeting for Spin and Hadron Physics at RIKEN

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