[en] 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

[en] The ¹H(e,e(prime)π⁺)n cross section was measured for a range of four-momentum transfer up to Q²=3.91 GeV² at values of the invariant mass, W, above the resonance region. The Q²-dependence of the longitudinal component is consistent with the Q²-scaling prediction for hard exclusive processes. This suggests that perturbative QCD concepts are applicable at rather low values of Q². Pion form factor results, while consistent with the Q²-scaling prediction, are inconsistent in magnitude with perturbative QCD calculations. The extraction of Generalized Parton Distributions from hard exclusive processes assumes the dominance of the longitudinal term. However, transverse contributions to the cross section are still significant at Q²=3.91 GeV²

[en] We have measured the nuclear transparency of the A(e,e' pi⁺) process in ²H,¹²C, ²⁷Al, ⁶³Cu and ¹⁹⁷Au targets. These measurements were performed at the Jefferson Laboratory over a four momentum transfer squared range Q² = 1.1 - 4.7 (GeV/c)². The nuclear transparency was extracted as the super-ratio of σ_Aσ_H from data to a model of pion-electroproduction from nuclei without pi-N final state interactions. The Q² and atomic number dependence of the nuclear transparency both show deviations from traditional nuclear physics expectations, and are consistent with calculations that include the quantum chromodynamical phenomenon of color transparency

[en] The quasielastic (e,e[prime]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

[en] The first measurements of the d(gamma,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 theta_cm = 37^o are consistent with the constituent counting rules for E_gamma∼> 4 GeV, while those at 70^o are consistent with the constituent counting rules for E_gamma ∼> 1.5 GeV

[en] The A(e,eiK+)YX reaction on H, D, ³He, and ⁴He was investigated in Hall C at CEBAF. Data were obtained for Q² ∼ 0.35 and 0.5 GeV² at 3.245 GeV. The missing mass spectra for both H and D are fitted with Monte-Carlo simulations incorporating peaks corresponding to Lambda production on the proton and Sigma production on both the proton and neutron. For D, the cross section ratio Sigma⁰/Sigma^- ∼ 2, and excess yield close to the thresholds for Lambda and Sigma production can be attributed to final-state interactions; models are compared to the data. The analysis of the data for the He targets is in a more preliminary state with broader quasi-free peaks resulting from the higher Fermi momenta. Evidence for bound Lambda-hypernuclear states is seen and other structure may be present

[en] Kaon electroproduction on hydrogen, deuterium and helium targets has been measured at a beam energy of 3.245 GeV and four-momentum transfer, Q², ranging from 0.34 to 0.5 GeV². Associated hyperon production off a nucleon in the deuteron exhibits a quasifree production mechanism. Excess yield close to the respective thresholds for Λ and Σ production is observed. This can be accounted for by final-state interaction between the electroproduced hyperon and the spectator nucleon. The effects predicted from three different hyperon-nucleon potentials are compared to the data. The measurement on the helium targets is the first ever performed. Very preliminary results are presented

[en] The A(e,eK+)X reaction has been investigated at Jefferson Laboratory. Data were taken for Q² approx. 0.35 GeV² at a beam energy of 3.245 GeV for 1H,3He and 4He targets. Evidence for Lambda-hypernuclear bound states is seen for 3,4He targets. This is the first time that the electroproduction of these hypernuclei has been observed