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Spin-Flavor Decomposition

Spin-Flavor Decomposition. J. P. Chen, Jefferson Lab PVSA Workshop, April 26-27, 2007, Brookhaven National Lab. Polarized Inclusive DIS, D u/u and D d/d from A 1 n /A 1 p Spin-Flavor decomposition in high- x (valence) region Polarized Semi-Incluisve DIS

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Spin-Flavor Decomposition

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  1. Spin-Flavor Decomposition J. P. Chen, Jefferson Lab PVSA Workshop, April 26-27, 2007, Brookhaven National Lab • Polarized Inclusive DIS, Du/u and Dd/d from A1n/A1p • Spin-Flavor decomposition in high-x (valence) region • Polarized Semi-Incluisve DIS • Spin-Flavor decomposition in moderate-x region • PolarizedParity-Violating DIS • A new window to study sea quark polarization • JLab 12 GeV upgrade and a large acceptance solenoid detector • A powerful tool for nucleon spin-flavor decomposition

  2. Unpolarized and Polarized Structure Functions

  3. Unpolarized Parton Distributions (CTEQ6) • After 40 years DIS experiments, unpolarized structure of the nucleon reasonably well understood. • High x valence quark dominating

  4. NLO Polarized Parton Distributions (AAC06)

  5. Polarized Inclusive DIS Valence Quark Spin-Flavor decomposition at high x

  6. World data for A1 Proton Neutron

  7. Precision A1n at High x from Hall AE99-117 • First precision A1n data at high x • Extracting valence quark spin distributions • Test our fundamental understanding of valence quark picture • SU(6) symmetry • Valence quark models • pQCD (with HHC) predictions • Quark orbital angular momentum • Crucial input for pQCD fit to PDF • PRL 92, 012004 (2004) • PRC 70, 065207 (2004)

  8. A1p/A1d Results from CLAS Proton Deuteron

  9. Naïve Extraction of Polarized Quark Distributions • Combining A1n and A1p results • Valence quark dominating at high x • u quark spin as expected • d quark spin stays negative! • Disagree with pQCD model calculations assuming HHC (hadron helicity conservation) • Quark orbital angular momentum • Consistent with valence quark models, pQCD PDF fits without HHC constraint, statistic model • Consistent with a new model from Feng Yuan et al. including OAM

  10. Projections for JLab at 11 GeV A1n at 11 GeV A1p at 11 GeV

  11. Spin Structure with the Solenoid at JLab 12 GeV • Program on spin structure with polarized target(s) and a solenoid • highest polarized luminosity: ~1036 • A solenoid with detector package (GEM, Lead-glass+ Cherenkov) large acceptance: ~700 msr for polarized  high luminosity and large acceptance • Inclusive DIS: improve by a factor of 10-100 A1 at high-x: 200 hours, high precision parity violating spin structure g3/g5 : first significant measurement • SIDIS: improve by a factor of 100-1000 spin-flavor decomposition (~2 orders improvement) transversity and TMDs,

  12. Solenoid detector for (SI)DIS GEMs Gas Cerenkov 3He target GEMs Calorimeter

  13. With Standard HMS+SHMS, 1800 hours (X. Zheng) • With Solenoid, 200 hours

  14. Polarized Semi-inclusive DIS Spin-Flavor decomposition at moderate x

  15. Flavor decomposition with SIDIS Duv and Ddv at JLab 11 GeV • With standard HMS+SHMS(see X. Jiang’s Talk) compared with HERMESWith Solenoid, 2 orders of magnitude improvement

  16. JLab @11 GeV Polarized Sea with SIDIS Polarized Sea • With standard HMS+SHMS (X. Jiang’s talk) compared with HERMESWith Solenoid, 2 orders of magnitude improvement

  17. Polarized Parity Violating DIS Sea quark polarization

  18. Longitudinal Target Single Spin Asymmetry • Unpolarized beam on longitudinally polarized target keep gZ interference terms, neglect Z2 terms g1gZ term can be eliminated by using positron beam

  19. PV-SSF in Naïve Parton Model • Naïve Parton Model: Put back into the general formula, we get g3 provides access to polarized sea quark distributions. Potential access to polarized strange quark distributions.

  20. Measure PV-TSSA with the Selonoid • At x=0.2, Q2=2.4, y=0.58, A~ 10-5-10-4 • Need high luminosity and large acceptance • Rate estimation with the Solenoid detector: 1000 hours beam, statistical precision for asymmetry will bea few x 10-5. A significant first measurement (~ a few s?)

  21. Projection of Collins/Sivers Asymmetries vs PT and x for p+ (60 days) • For one z bin (0.5-0.6) • Will obtain 4 z bins (0.3-0.7) • Also p- at same time • With upgraded PID for K+ and K-

  22. Summary Spin-Flavor decomposition: • Polarized inclusive DIS in high-x region • Valence quark polarization • Polarized semi-inclusive DIS in moderate-x region • Valence and sea quark polarization • Polarized parity violating DIS • A new tool to study sea quark polarization • A large acceptance solenoid with high luminosity • 700 msr, 1036 polarized (n) luminosity • Improvement of a factor of 10-100 in acceptance*luminosity

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