[en] We report on a study of the longitudinal to transverse cross section ratio, R=σ_L/σ_T, at low values of x and Q², as determined from inclusive inelastic electron-hydrogen and electron-deuterium scattering data from Jefferson Laboratory Hall C spanning the four-momentum transfer range 0.06< Q²<2.8 GeV². Even at the lowest values of Q², R remains nearly constant and does not disappear with decreasing Q², as might be expected. We find a nearly identical behavior for hydrogen and deuterium

[en] The _Λ^3,4H and _Λ⁴H hypernuclear bound states have been observed for the first time in kaon electroproduction on ^3,4He targets. The production cross sections have been determined at Q²=0.35 GeV² and W=1.91 GeV. For either hypernucleus the nuclear form factor is determined by comparing the angular distribution of the ^3,4He(e,e^'K⁺)_Λ^3,4H processes to the elementary cross section ¹H(e,eK⁺)Λ on the free proton, measured during the same experiment

[en] The ratio G_cⁿ/G_mⁿ of the electric to the magnetic form factor of the neutron has been measured by analyzing the polarization of the recoiling neutron in quasi-elastic scattering of longitudinally polarized electrons from deuterium at the Q² values of 0.45, 1.15, and 1.47 (GeV/c)². The experiment has been performed in Hall C of the Thomas Jefferson National Accelerator Facility. With G_mⁿ being known G can be deduced. The preliminary results show that the lowest Q² points follow the Galster parameterization and that the 1.47 (GeV/c)² point rises above this parameterization

[en] Measurements of the proton and deuteron F₂ structure functions are presented. The data, taken at Jefferson Lab Hall C, span the four-momentum transfer range 0.06< Q²<2.8 GeV² and Bjorken x values from 0.009 to 0.45, thus extending the knowledge of F₂ to low values of Q² at low x. Next-to-next-to-leading-order calculations using recent parton distribution functions start to deviate from the data for Q²<2 GeV² at the low and high x values. Down to the lowest value of Q², the structure function is in good agreement with a parametrization of F₂ based on data that have been taken at much higher values of Q² or much lower values of x, and which are constrained by data at the photon point. The ratio of the deuteron and proton structure functions at low x remains well described by a logarithmic dependence on Q² at low Q².

[en] We studied the electroproduction of the Δ(1232) resonance via the reaction p(e,e^'p)π⁰ at four-momentum transfers Q²=2.8 and 4.0 GeV² . This is the highest Q² for which exclusive resonance electroproduction has ever been observed. Decay angular distributions for Δ→pπ⁰ were measured over a wide range of barycentric energies covering the resonance. The N - Δ transition form factor G^*_M and ratios of resonant multipoles E₁₊/M₁₊ and S₁₊/M₁₊ were extracted from the decay angular distributions. These ratios remain small, indicating that perturbative QCD is not applicable for this reaction at these momentum transfers. copyright 1998 The American Physical Society

No abstract available

[en] The ¹H( e,thinspe^'K⁺)Λ reaction was studied as a function of the squared four-momentum transfer, Q² , and the virtual photon polarization, var-epsilon . For each of four Q² settings, 0.52, 0.75, 1.00, and 2.00 (GeV/c)² , the longitudinal and transverse virtual photon cross sections were extracted in measurements at three virtual photon polarizations. The Q² dependence of the σ_L/σ_T ratio differs significantly from current theoretical predictions. This, combined with the precision of the measurement, implies a need for revision of existing calculations. copyright 1998 The American Physical Society