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| 2. |
- Wijesooriya, K, et al.
(författare)
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Polarization measurements in high-energy deuteron photodisintegration
- 2001
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 86:14, s. 2975-2979
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Tidskriftsartikel (refereegranskat)abstract
- We present measurements of the recoil proton polarization for the d(γ⃗,p⃗)n reaction at θc.m. = 90° for photon energies up to 2.4 GeV. These are the first data in this reaction for polarization transfer with circularly polarized photons. The induced polarization py vanishes above 1 GeV, contrary to meson-baryon model expectations, in which resonances lead to large polarizations. However, the polarization transfer Cx does not vanish above 1 GeV, inconsistent with hadron helicity conservation. Thus, we show that the scaling behavior observed in the d(γ,p)ncross sections is not a result of perturbative QCD. These data should provide important tests of new nonperturbative calculations in the intermediate energy regime.
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| 3. |
- Schulte, EC, et al.
(författare)
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High energy angular distribution measurements of the exclusive deuteron photodisintegration reaction
- 2002
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Ingår i: Physical Review C (Nuclear Physics). - : American Physical Society. - 0556-2813 .- 1089-490X. ; 66:4
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Tidskriftsartikel (refereegranskat)abstract
- The first complete measurements of the angular distributions of the two-body deuteron photodisintegration differential cross section at photon energies above 1.6 GeV were performed at the Thomas Jefferson National Accelerator Facility. The results show a persistent forward-backward asymmetry up to E-gamma=2.4 GeV, the highest-energy measured in this experiment. The Hard Rescattering and the Quark-Gluon string models are in fair agreement with the results.
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| 4. |
- Wijesooriya, K, et al.
(författare)
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Polarization measurements in neutral pion photoproduction
- 2002
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 66:3
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Tidskriftsartikel (refereegranskat)abstract
- We present measurements of the recoil proton polarization for the H-1((γ) over right arrow,(p) over right arrow)pi(0) reaction for theta(c.m.)(pi) = 60degrees-135degrees and for photon energies up to 4.1 GeV. These are the first data in this reaction for polarization transfer with circularly polarized photons. Various theoretical models are compared with the results. No evidence for hadron helicity conservation is observed. Models that employ factorization are not favored. It appears from the strong angular dependence of the induced polarization at photon energies of 2.5 and 3.1 GeV that a relatively high spin resonance or background amplitude might exist in this energy region.
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| 5. |
- Amarian, M, et al.
(författare)
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Measurement of the Generalized Forward Spin Polarizabilities of the Neutron
- 2004
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Ingår i: Physical Review Letters. - 1079-7114. ; 93
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Tidskriftsartikel (refereegranskat)abstract
- The generalized forward spin polarizabilities 0 and LT of the neutron have been extracted for the first time in a Q2 range from 0.1 to 0.9 GeV2. Since 0 is sensitive to nucleon resonances and LT is insensitive to the resonance, it is expected that the pair of forward spin polarizabilities should provide benchmark tests of the current understanding of the chiral dynamics of QCD. The new results on LT show significant disagreement with chiral perturbation theory calculations, while the data for 0 at low Q2 are in good agreement with a next-to-leading-order relativistic baryon chiral perturbation theory calculation. The data show good agreement with the phenomenological MAID model.
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| 6. |
- Amarian, M, et al.
(författare)
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Q2 Evolution of the Neutron Spin Structure Moments using a He-3 Target
- 2004
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Ingår i: Physical Review Letters. - 1079-7114. ; 92
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Tidskriftsartikel (refereegranskat)abstract
- We have measured the spin structure functions g1 and g2 of 3He in a double-spin experiment by inclusively scattering polarized electrons at energies ranging from 0.862 to 5.058 GeV off a polarized 3He target at a 15.5° scattering angle. Excitation energies covered the resonance and the onset of the deep inelastic regions. We have determined for the first time the Q2 evolution of 1(Q2)=g1(x,Q2)dx, 2(Q2)=g2(x,Q2)dx, and d2(Q2)=x2[2g1(x,Q2)+3g2(x,Q2)]dx for the neutron in the range 0.1Q20.9 GeV2 with good precision. 1(Q2) displays a smooth variation from high to low Q2. The Burkhardt-Cottingham sum rule holds within uncertainties and d2 is nonzero over the measured range.
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| 7. |
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