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Drell-Yan: SI-DIS sideways

Drell-Yan: SI-DIS sideways. Paul E. Reimer The Drell-Yan Process Parton Distributions from Drell-Yan Nuclear Pions/Antishadowing in Antiquarks. e -. e -.  *. proton. hadron. proton. } X. proton. } X.  -. proton.  +. } X. Why talk about Drell-Yan at SIR workshop?.

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Drell-Yan: SI-DIS sideways

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  1. Drell-Yan: SI-DIS sideways Paul E. Reimer The Drell-Yan Process Parton Distributions from Drell-Yan Nuclear Pions/Antishadowing in Antiquarks

  2. e- e- * proton hadron proton }X proton }X - proton + }X Why talk about Drell-Yan at SIR workshop? • 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) Paul E. Reimer Semi-Inclusive Reactions 2005

  3. proton }X - proton + }X xtarget xbeam Probing quark structure with Drell-Yan scattering (Fixed Target) Leading Order • Detector acceptance chooses range in xtarget and xbeam. • xF = xbeam – xtarget > 0 • high-x Valence Beam quarks. • Low/interm.-x sea Target quarks. Paul E. Reimer Semi-Inclusive Reactions 2005

  4. Fermilab Accelerator Complex:Fixed Target Program Fixed Target Beamlines Tevatron 800 GeV Main Injector 120 GeV Paul E. Reimer Semi-Inclusive Reactions 2005

  5. Fermilab Drell-Yan Experiments The future: FNAL E906 • Data in 2009?? • 1H, 2H, and nuclear targets • 120 GeV proton Beam The (very successful) past: FNAL E866/NuSea • Data in 1996-1997 • 1H, 2H, and nuclear targets • 800 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!! Paul E. Reimer Semi-Inclusive Reactions 2005

  6. What is the structure of the nucleon: What is d-bar / u-bar in the proton? • Select xbÀ xt 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)

  7. 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.

  8. LA-LP-98-56 What is the structure of the nucleon: What produces the nucleon sea? • pQCD ! Gluon splitting? • Meson Cloud? Chiral Solitons? Instantons? • Models describe well, but not —pQCD becoming dominant? Peng et al. Soon lattice moment analysis may also weigh in.

  9. 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 MRST and CTEQ: d/u!0 as x!1 • Reach high-x through beam proton—Large xF)large xbeam. • 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.

  10. 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.

  11. Parton Energy Loss • Colored parton moving in strongly interacting media. • Only initial state interactions are important—no final state strong interactions. • 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.

  12. Experiment Runs Expt. Funded Magnet Design Experiment And construction Construction Proposed Jan. 2004 Publications 2005 2006 2007 2008 2009 2010 E906 Schedule • 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

  13. Drell-Yan at Fermilab • 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? • Answers from E906! • Significant increase in physics reach over earlier Drell-Yan exp. • Scheduled to run in 2009

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