1. A U.S. Department of Energy Office of Science Laboratory Operated by The University of Chicago Argonne National Laboratory Office of Science U.S. Department of Energy Drell-Yan: SI-DIS sideways Paul E. Reimer The Drell-Yan Process Parton Distributions from Drell-Yan Nuclear Pions/Antishadowing in Antiquarks

2. Pioneering Science and Technology Office of Science U.S. Department of Energy 2 20 May 2004Paul E. Reimer Semi-Inclusive Reactions 2005 e-e- e-e- proton ** hadron }X}X Why talk about Drell-Yan at SIR workshop? proton }X}X }X}X -- ++ Similar Physics Goals -Parton level understanding of nucleon -Electromagnetic probe Differences -Timelike (Drell-Yan) vs. spacelike (DIS) virtual photon. -Hadron beam and convolution of parton distributions (Drell-Yan) -Factorazion/Hadronization (SI-DIS)

3. Pioneering Science and Technology Office of Science U.S. Department of Energy 3 20 May 2004Paul E. Reimer Semi-Inclusive Reactions 2005 Probing quark structure with Drell-Yan scattering (Fixed Target) Leading Order x target x beam Detector acceptance chooses range in x target and x beam. x F = x beam – x target > 0 high-x Valence Beam quarks. Low/interm.-x sea Target quarks. proton }X}X }X}X -- ++

4. Pioneering Science and Technology Office of Science U.S. Department of Energy 4 20 May 2004Paul E. Reimer Semi-Inclusive Reactions 2005 Fermilab Accelerator Complex: Fixed Target Program Main Injector 120 GeV Tevatron 800 GeV Fixed Target Beamlines

5. Pioneering Science and Technology Office of Science U.S. Department of Energy 5 20 May 2004Paul E. Reimer Semi-Inclusive Reactions 2005 Fermilab Drell-Yan Experiments FNAL E866/NuSea The (very successful) past: FNAL E866/NuSea Data in 1996-1997 1 H, 2 H, and nuclear targets 800 GeV proton beam FNAL E906 The future: FNAL E906 Data in 2009?? 1 H, 2 H, and nuclear targets 120 GeV proton Beam Cross section scales as 1/s -7£ that of 800 GeV beam Backgrounds, primarily from J/  decays scale as s -7£ Luminosity for same detector rate as 800 GeV beam 50£ statistics!!

6. Pioneering Science and Technology Office of Science U.S. Department of Energy 6 20 May 2004Paul E. Reimer Semi-Inclusive Reactions 2005 FNAL E906 Collaboration Abilene Christian University Donald Isenhower, Mike Sadler, Rusty Towell Argonne National Laboratory John Arrington, Don Geesaman *, Kawtar Hafidi, Roy Holt, Hal Jackson, Paul E. Reimer *, David Potterveld University of Colorado Ed Kinney Fermi National Accelerator Laboratory Chuck Brown University of Illinois Jen-Chieh Peng * Co-Spokespersons Los Alamos National Laboratory Gerry Garvey, Mike Leitch, Pat McGaughey, Joel Moss Rutgers University Ron Gilman, Charles Glashausser, Xiaodong Jaing, Ron Ransome Texas A & M University Carl Gagliardi, Bob Tribble, Maxim Vasiliev Thomas Jefferson National Accelerator Facility Dave Gaskell Valparaiso University Don Koetke

7. Pioneering Science and Technology Office of Science U.S. Department of Energy 7 20 May 2004Paul E. Reimer Semi-Inclusive Reactions 2005 FNAL E866/NuSea Collaboration 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 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

8. Pioneering Science and Technology Office of Science U.S. Department of Energy 8 What is the structure of the nucleon: What is d-bar / u-bar in the proton? Select x b À x t to isolate first term (detector acceptance will do this). Study ratio of cross sections for deuterium to hydrogen (In analysis, we use a full Next-to- Leading order cross section calculation)

9. Pioneering Science and Technology Office of Science U.S. Department of Energy 9 What is the structure of the nucleon: What is d-bar / u-bar in the proton? Parton Distributions PDF fits are completely dominated by E866 data Uncertainties of PDF fits are dictated by E866 uncertainties. E906 will significantly extend these measurements and improve on uncertainty. Impact on sensitivity of Collider/LHC tests of the Standard Model (understanding of background). Origins of the Proton Sea Models explain d-bar ¸ u-bar. No theory expects the results seen for x ¸ 0.3.

10. Pioneering Science and Technology Office of Science U.S. Department of Energy 10 pQCD ! Gluon splitting? Meson Cloud? Chiral Solitons? Instantons? Models describe well, but not —pQCD becoming dominant? LA-LP-98- 56 Soon lattice moment analysis may also weigh in. What is the structure of the nucleon: What produces the nucleon sea? Peng et al.

11. Pioneering Science and Technology Office of Science U.S. Department of Energy 11 Radiative corrections calculations are now finished—small effect. Fermilab E906 will add much more precise high-x data. Drell-Yan Absolute Cross Sections: Proton Structure as x! 1 Reach high-x through beam proton—Large x F )large x beam. Proton-Proton—no nuclear corrections—4u(x) + d(x) Proton-deuterium (cross check) agrees with proton-proton data. Parton distributions overestimate cross section. Working with CTEQ to incorporate data in global PDF fits. MRST and CTEQ: d/u!0 as x!1

12. Pioneering Science and Technology Office of Science U.S. Department of Energy 12 E906 will clearly challenge revised predictions. Models sharply diverge from unity at larger x What is the structure of nucleonic matter: Where are the nuclear pions? Antiquark enhancement expected from Nuclear Pions. Early predictions (Berger and Coester) proved false by Fermilab E772 Drell-Yan data. Note that E772 has relatively large uncertainties, especially as x increases.

13. Pioneering Science and Technology Office of Science U.S. Department of Energy 13 What is the structure of nucleonic matter: How do sea quark distrib. differ in a nucleus? Comparison with Deep Inelastic Scattering Antishadowing not seen in Drell- Yan—Valence only effect?— better statistical precision needed—E906. sea Intermediate-x sea PDF’s set by -DIS on iron—unknown nuclear effects. What can the sea parton distributions tell us about nuclear binding?

14. Pioneering Science and Technology Office of Science U.S. Department of Energy 14 Colored parton moving in strongly interacting media. Only initial state interactions are important—no final state strong interactions. Parton Energy Loss E866 Data are consistent with no energy loss Treatment of parton propagation length and shadowing are critical Johnson et al. find 2.2 GeV/fm Energy loss / 1/s—larger at 120 GeV Important to understand RHIC data.

15. Pioneering Science and Technology Office of Science U.S. Department of Energy 15 E906 Schedule 200820072010 Publications 2006 Expt. Funded 2009 Magnet DesignExperiment And constructionConstruction Proposed Jan. 2004 Experiment Runs 2005 Boost difference between 800 and 120 GeV requires shorter experiment. -Fabrication of new coils for M1 magnet Other items: -New Station 1 to handle higher rate -Replace some very old scintillators, additional phototubes Approx. Cost $2M

16. Pioneering Science and Technology Office of Science U.S. Department of Energy 16 Drell-Yan at Fermilab Answers from E906! -Significant increase in physics reach over earlier Drell-Yan exp. -Scheduled to run in 2009 What is the structure of the nucleon? -d-bar/u-bar at intermediate-x -Parton distributions as x!1 What is the structure of nucleonic matter? -Where are the nuclear pions? -Is anti-shadowing a valence effect? -Do partons lose energy?