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1.
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B. Hu et al.
Show Abstract
The recoil proton polarization was measured in the 2H(e→,e′p→)n reaction in Hall A of the Thomas Jefferson National Accelerator Facility. The electron kinematics were centered on the quasielastic peak (xBj≈1) and included three values of the squared four-momentum transfer, Q2=0.43,1.00 and 1.61 (GeV/c)2. For Q2=0.43 and 1.61 (GeV/c)2, the missing momentum, pm, was centered at zero, whereas for Q2=1.00 (GeV/c)2 two values of pm were chosen: 0 and 174 MeV/c. At low pm, the Q2 dependence of the longitudinal polarization, Pz′, is not well described by a state-of-the-art calculation. Further, at higher pm, a 3.5σ discrepancy was observed in the transverse polarization, Px′. Understanding the origin of these discrepancies is important to confidently extract the neutron electric form factor from the analogous 2H(e→,e′n→)p experiment.
Phys. Rev. C 73, 064004 (2006)
Cited 1 times
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2.
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E. C. Schulte et al.
Show 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 Eγ=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.
Phys. Rev. C 66, 042201 (2002)
Cited 6 times
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3.
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K. Wijesooriya et al.
Show Abstract
We present measurements of the recoil proton polarization for the 1H(γ→,p→)π0 reaction for θc.m.π=60°–135° 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.
Phys. Rev. C 66, 034614 (2002)
Cited 11 times
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4.
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O. Gayou et al. (The Jefferson Lab Hall A Collaboration)
Show Abstract
We present measurements of the ratio of the proton elastic electromagnetic form factors, μpGEp/GMp. The Jefferson Lab Hall A Focal Plane Polarimeter was used to determine the longitudinal and transverse components of the recoil proton polarization in ep elastic scattering; the ratio of these polarization components is proportional to the ratio of the two form factors. These data reproduce the observation of Jones et al. [Phys. Rev. Lett. 84, 1398 (2000)], that the form factor ratio decreases significantly from unity above Q2=1 GeV2.
Phys. Rev. C 64, 038202 (2001)
Cited 55 times
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5.
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K. Wijesooriya et al. (Jefferson Lab Hall A Collaboration)
Show Abstract
We present measurements of the recoil proton polarization for the d(γ→,p→)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)n cross sections is not a result of perturbative QCD. These data should provide important tests of new nonperturbative calculations in the intermediate energy regime.
Phys. Rev. Lett. 86, 2975 (2001)
Cited 19 times
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6.
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G. M. Huber et al. (The TAGX Collaboration)
Show Abstract
The 3He(γ,π±p) reactions were measured simultaneously over a tagged photon energy range of 800<~Eγ<~1120 MeV, well above the Δ resonance region. An analysis was performed to kinematically isolate Δ knockout events from conventional Δ photoproduction events, and a statistically significant excess of π+p events was identified, consistent with Δ++ knockout. Two methods were used to estimate the ΔNN probability in the 3He ground state corresponding to the observed knockout cross section. The first gave a lower probability limit of 1.5±0.6±0.5 %; the second yielded an upper limit of about 2.6%.
Phys. Rev. C 62, 044001 (2000)
Cited 4 times
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