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Target Single Spin Asymmetries using Vertically Polarized 3 He

Target Single Spin Asymmetries using Vertically Polarized 3 He. Todd Averett—College of William and Mary Three experiments will measure these SSA’s One is running concurrently with transversity Two others tentatively scheduled for early ‘09.

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Target Single Spin Asymmetries using Vertically Polarized 3 He

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  1. Target Single Spin Asymmetries using Vertically Polarized 3He • Todd Averett—College of William and Mary • Three experiments will measure these SSA’s • One is running concurrently with transversity • Two others tentatively scheduled for early ‘09.

  2. Unpolarized electron scattering from vertically (normally) polarized 3He. Three experiments will measure Ay: Quasi-elastic, DIS, and QE 3He(e,e’n).

  3. (Christ-Lee Theorem)

  4. Expected Results

  5. Q2=0.5, 0.75, 1.0 GeV2

  6. New polarized target now achieving 65% in-beam polarization due to hybrid alkali and narrowed lasers.

  7. What about two-photon exchange in inclusive DIS? • The formalism remains the same: • Ay=0 for 1-photon exchange • For DIS, one assumes that the scattering is dominated by two photon • exchange with a single quark. • For non-interacting quarks, Ay=0 for two-photon exchange! • Afanasev, Strikman, Weiss (Phys.Rev.D77:014028,2008) predict Ay~10-4 using a model based on the quark transversity distribution. • This means the SSA should change by two orders of magnitude from DIS • to QE kinematics. This is a direct study of the “transition” from hadron-like • to parton-like behavior. • This is being measured in Hall A concurrent with the transversityexperiment using • BigBite Spectrometer. • HAPPEX DAQ and Hall A Lumi’s are being used to monitor the luminosity asymmetry. • (Joe Katich-WM graduate thesis student)

  8. SSA in quasi-elastic 3He(e,e’n) • By detecting the outgoing neutron, the SSA is sensitive to FSI • PWIA Calculations predict Ay=0 • Theoretical models with FSI, 3He wavefunction, etc predict Ay=20-45% • Unpublished measurement at NIKEF measured large Ay~50% at Q2=0.2 GeV2!!! Golak Laget, Nagorney

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