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1.
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V. Tadevosyan et al. Jefferson Lab Fπ Collaboration
Show Abstract
The data analysis for the reaction 1H(e,e'π+)n, which was used to determine values for the charged pion form factor Fπ for values of Q2= 0.6–1.6 GeV2, has been repeated with careful inspection of all steps and special attention to systematic uncertainties. Also the method used to extract Fπ from the measured longitudinal cross section was critically reconsidered. Final values for the separated longitudinal and transverse cross sections and the extracted values of Fπ are presented.
Phys. Rev. C 75, 055205 (2007)
Cited 9 times
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2.
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M. E. Christy et al.
Show Abstract
We report on precision measurements of the elastic cross section for electron-proton scattering performed in Hall C at Jefferson Lab. The measurements were made at 28 distinct kinematic settings covering a range in momentum transfer of 0.4<Q2<5.5 (GeV∕c)2. These measurements represent a significant contribution to the world’s cross section data set in the Q2 range, where a large discrepancy currently exists between the ratio of electric to magnetic proton form factors extracted from previous cross section measurements and that recently measured via polarization transfer in Hall A at Jefferson Lab. This data set shows good agreement with previous cross section measurements, indicating that if a heretofore unknown systematic error does exist in the cross section measurements, then it is intrinsic to all such measurements.
Phys. Rev. C 70, 015206 (2004)
Cited 33 times
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3.
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D. Dutta et al.
Show Abstract
We report the results from a systematic study of the quasielastic (e,e′p) reaction on 12C, 56Fe, and 197Au performed at Jefferson Lab. We have measured nuclear transparency and extracted spectral functions (corrected for radiation) over a Q2 range of 0.64–3.25 (GeV∕c)2 for all three nuclei. In addition, we have extracted separated longitudinal and transverse spectral functions at Q2 of 0.64 and 1.8 (GeV∕c)2 for these three nuclei (except for 197Au at the higher Q2). The spectral functions are compared to a number of theoretical calculations. The measured spectral functions differ in detail but not in overall shape from most of the theoretical models. In all three targets the measured spectral functions show considerable excess transverse strength at Q2=0.64 (GeV∕c)2, which is much reduced at 1.8 (GeV∕c)2.
Phys. Rev. C 68, 064603 (2003)
Cited 18 times
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4.
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K. Garrow et al.
Show Abstract
The quasielastic (e,e′p) reaction was studied on targets of deuterium, carbon, and iron up to a value of momentum transfer Q2 of 8.1 (GeV/c)2. A nuclear transparency was determined by comparing the data to calculations in the plane-wave impulse approximation. The dependence of the nuclear transparency on Q2 and the mass number A was investigated in a search for the onset of the color transparency phenomenon. We find no evidence for the onset of color transparency within our range of Q2. A fit to the world’s nuclear transparency data reflects the energy dependence of the free-proton–nucleon cross section.
Phys. Rev. C 66, 044613 (2002)
Cited 20 times
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5.
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E. C. Schulte et al.
Show Abstract
The first measurements of the d(γ,p)n differential cross section at forward angles and photon energies above 4 GeV were performed at the Thomas Jefferson National Accelerator Facility (JLab). The results indicate evidence of an angular dependent scaling threshold. Results at θcm = 37° are consistent with the constituent counting rules for Eγ≳4 GeV, while those at 70° are consistent with the constituent counting rules for Eγ≳1.5 GeV.
Phys. Rev. Lett. 87, 102302 (2001)
Cited 12 times
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6.
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J. Arrington et al.
Show Abstract
Inclusive electron scattering data are presented for 2H, C, Fe, and Au targets at an incident electron energy of 4.045 GeV for a range of momentum transfers from Q2=1 to 7 (GeV/c)2. Data were taken at Jefferson Laboratory for low values of energy loss, corresponding to values of Bjorken x≳1. The structure functions do not show scaling in x in this range, where inelastic scattering is not expected to dominate the cross section. The data do show scaling, however, in the Nachtmann variable ξ. This scaling appears to be the result of Bloom- Gilman duality in the nucleon structure function combined with the Fermi motion of the nucleons in the nucleus. The resulting extension of scaling to larger values of ξ opens up the possibility of accessing nuclear structure functions in the high-x region at lower values of Q2 than previously believed.
Phys. Rev. C 64, 014602 (2001)
Cited 20 times
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7.
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J. Volmer et al. (The Jefferson Lab Fπ Collaboration)
Show Abstract
Separated longitudinal and transverse structure functions for the reaction 1H(e,e′π+)n were measured in the momentum transfer region Q2 = 0.6–1.6 (GeV/c)2 at a value of the invariant mass W = 1.95 GeV. New values for the pion charge form factor were extracted from the longitudinal cross section by using a recently developed Regge model. The results indicate that the pion form factor in this region is larger than previously assumed and is consistent with a monopole parametrization fitted to very low Q2 elastic data.
Phys. Rev. Lett. 86, 1713 (2001)
Cited 61 times
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8.
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I. Niculescu et al.
Show Abstract
A newly obtained sample of inclusive electron-nucleon scattering data has been analyzed for precision tests of quark-hadron duality. The data are in the nucleon resonance region, and span the range 0.3<Q2<5.0 (GeV/c)2. Duality is observed both in limited and extended regions around the prominent resonance enhancements. Higher twist contributions to the F2 structure function are found to be small on average, even in the low Q2 regime of ≈0.5 (GeV/c)2. Using duality, an average scaling curve is obtained. In all cases, duality appears to be a nontrivial property of the nucleon structure function.
Phys. Rev. Lett. 85, 1186 (2000)
Cited 51 times
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9.
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I. Niculescu et al.
Show Abstract
A newly obtained data sample of inclusive electron-nucleon scattering from both hydrogen and deuterium targets is analyzed. These JLab data span the nucleon resonance region up to four-momentum transfers of 5 (GeV/c)2. The data are found to follow an average scaling curve. The inclusion of low-momentum transfer data yields a scaling curve resembling deep inelastic neutrino-nucleus scattering data, suggesting a sensitivity to valencelike structure only.
Phys. Rev. Lett. 85, 1182 (2000)
Cited 42 times
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10.
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D. Dutta et al.
Show Abstract
A separation of the longitudinal and transverse 12C(e,e′p) cross sections in the quasifree region has been performed in parallel kinematics at Q2 of 0.64 and 1.8 GeV2 for initial proton momentum <80 MeV. The separated transverse and longitudinal spectral functions at Q2=0.64 GeV2 show significant differences for missing energy between 25 and 60 MeV indicating a breakdown in the single nucleon knockout picture. The transverse spectral functions exhibit definite momentum transfer dependence.
Phys. Rev. C 61, 061602 (2000)
Cited 8 times
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11.
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D. G. Meekins et al.
Show Abstract
The differential cross section for 2H(γ,d)π0 has been measured at deuteron center-of-mass angles of 90° and 136°. This work reports the first data for this reaction above a photon energy of 1 GeV, and permits a test of the apparent constituent counting rule and reduced nuclear amplitude behavior as observed in elastic ed scattering. Measurements were performed up to a photon energy of 4.0 GeV, and are in good agreement with previous lower energy measurements. Overall, the data are inconsistent with both constituent-counting rule and reduced nuclear amplitude predictions.
Phys. Rev. C 60, 052201 (1999)
Cited 2 times
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12.
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J. Arrington et al.
Show Abstract
Inclusive electron scattering is measured with 4.045 GeV incident beam energy from C, Fe, and Au targets. The measured energy transfers and angles correspond to a kinematic range for Bjorken x>1 and momentum transfers from Q2 = 1–7 (GeV/c)2. When analyzed in terms of the y-scaling function the data show for the first time an approach to scaling for values of the initial nucleon momenta significantly greater than the nuclear matter Fermi momentum (i.e., >0.3 GeV/c).
Phys. Rev. Lett. 82, 2056 (1999)
Cited 35 times
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13.
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C. Bochna et al.
Show Abstract
The first measurements of the differential cross section for the d(γ,p)n reaction up to 4.0 GeV were performed at the Continuous Electron Beam Accelerator Facility (CEBAF) at Thomas Jefferson Laboratory. We report the cross sections at the proton center-of-mass angles of 36°, 52°, 69°, and 89°. These results are in reasonable agreement with previous measurements at lower energy. The 89° and 69° data show constituent-counting-rule behavior up to 4.0 GeV photon energy. The 52° and 36° data disagree with the counting-rule behavior. The quantum chromodynamics (QCD) model of nuclear reactions involving reduced amplitudes disagrees with the present data.
Phys. Rev. Lett. 81, 4576 (1998)
Cited 27 times
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14.
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D. Abbott et al.
Show Abstract
The ( e,e′p) reaction was studied on targets of C, Fe, and Au at momentum transfers squared Q2 of 0.6, 1.3, 1.8, and 3.3 GeV2 in a region of kinematics dominated by quasifree electron-proton scattering. Missing energy and missing momentum distributions are reasonably well described by plane wave impulse approximation calculations with Q2 and A dependent corrections that measure the attenuation of the final state protons.
Phys. Rev. Lett. 80, 5072 (1998)
Cited 25 times
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