Neutron (3He) spin structure in the resonance region

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Neutron (3He) spin structurein the resonance
region

• Patricia Solvignon
• Temple University, Philadelphia
• For the JLAB Hall A and E01-012 Collaborations

First Workshop on Quark-Hadron Duality and the
Transition to pQCD
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Motivations

• Understand transition between partons and hadrons
  
• Study of higher twists
• Spin and flavor dependence of quark-hadron
  duality
• Access high xbj region if duality is demonstrated
  and well understood

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Hint of duality
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The E01-012 experiment
Spokepeople N. Liyanage, J-P. Chen, Seonho
Choi Graduate Student P. Solvignon

• Ran in January-February 2003
• Inclusive experiment 3He(e,e)X
• Measured polarized cross-sections differences and
  asymmetries
• Form g1, g2, A1 and A2 for 3He
• Test duality on the neutron SSF

?
?
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The experimental setup

• Polarized e- beam at 3, 4 and 5 GeV Pavg
  (77?3)
• Both HRS in symmetric config. at 25o and 32o ?
  Double statistics ? Control systematics
• PID Cerenkov EM calo. ? ?/e reduced by 104 ?
  ?(e-)gt99

JLab HALL A
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Polarized 3He target
Spin exchange between optically pumped Rb and 3He

• Longitudinal and transverse configurations
• High luminosity 1036 s-1 cm-2
• 2 independent polarimetries NMR and EPR

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Data analysis
??? - ???
??? - ??? A//raw ???? A? raw ????
??? ???
??? ???

• Generate asymmetries
• Measure unpolarized cross section
• Form polarized cross sections differences
• Can also get Born asymmetries

?oborn ?oraw - 2(?N2/ ?3He)?N R.C.
??//(?)raw 2 A//(?) ?o ??//(?) ??//(?)raw
R.C.
A//(?) ??//(?) / 2?oborn
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Polarized structure functions
Extract g1 and g2 directly from our data
MQ2? E 1 g1 ??? ? ???
4?e2 E E E
(??// tan(?/2) ??? )
(- ??//
MQ2?2 1 g2 ??? ?????
4?e2 2E(E E)
E E cos? ????? Esin?
??? )
Need external input of R to form A1 and A2
A// ? A? A1
???? - ???? D(1 ??) d(1 ??)
? A// A? A2
???? ???? D(1 ??) d(1 ??)
(D and d depend of R)
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Elastic asymmetry
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Asymmetries
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Comparison of both HRS
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Nitrogen cross sections
Nitrogen dilution fN2 2 (?N2/ ?3He ) ?N ?N
/50
QFS model from J.W. Lightbody and J.S. OConnell
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Unpolarized cross sections
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Unpolarized cross sections
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Polarized structure function g1
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Polarized structure function g1
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Polarized structure function g1
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Polarized structure function g1
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Polarized structure function g1
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Spin asymmetry A1
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Spin asymmetry A1
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Spin asymmetry A1
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Spin asymmetry A1
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Spin asymmetry A1
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Spin asymmetry A2
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Conclusion

• E01-012 provides precision data of SSF on neutron
  (3He) for 1.0 lt Q2 lt 4.0 (GeV/c) 2
• Direct extraction of g1 and g2 from our data
• Overlap between E01-012 resonance data and DIS
  ? test of Quark-hadron duality for neutron and
  nuclei SSF
• E01-012 data combined with proton data ?
  test of spin-flavor dependence of duality
• Our data can also be used to extract moments of
  SSF (e.g. GDH sum rule, d2, BC sum rule)

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Outlook
Extraction of the neutron SSF
Final results by the end of 2005
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Extra slides
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Polarized structure function g2
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Spin asymmetry A1