[en] The experimental and theoretical status of elastic electron scattering from the nucleon is reviewed. As a consequence of new experimental facilities, data of unprecedented precision have recently become available for the electromagnetic and the strange form factors of the nucleon

[en] The plans for upgrading the CEBAF accelerator at Jefferson Lab to 12 GeV are presented. The research program supporting that upgrade are illustrated with a few selected examples. The instrumentation under design to carry out that research program is discussed. Finally, a conceptual design of a future upgrade which combines a 25 GeV fixed-target facility and an electron-ion collider facility at a luminosity of up to 10³⁵ cm^-2s^-1 and a CM energy of over 40 GeV

[en] We review the experimental and theoretical status of elastic electron scattering and elastic low-energy photon scattering (with both real and virtual photons) from the nucleon. As a consequence of new experimental facilities and new theoretical insights, these subjects are advancing with unprecedented precision. These reactions provide many important insights into the spatial distributions and correlations of quarks in the nucleon

[en] The 2H(e,e'p)n cross section was measured in Hall A of the Thomas Jefferson National Accelerator Facility (JLab) in quasielastic kinematics (x=0.96) at a four-momentum transfer squared, Q²=0.67 (GeV/c)². The experiment was performed in fixed electron kinematics for recoil momenta from zero to 550 MeV/c. Though the measured cross section deviates by 1-2 sigma from a state-of-the-art calculation at low recoil momenta, it agrees at high recoil momenta where final state interactions (FSI) are predicted to be large

[en] A high quality beam of linearly polarized photons of several GeV will become available with the coherent bremsstrahlung technique at JLab. We have developed a polarimeter which requires about two meters of the beam line, has an analyzing power of 20% and an efficiency of 0.02%. The layout and first results of a polarimeter test on the laser back-scattering photon beam at Spring-8/LEPS are presented

[en] Color polarizabilities of the neutron are extracted from data on the lowest moment of the spin-dependent g1 structure function. New data in the resonance region from Jefferson Lab at Q² <∼ 1 GeV², in combination with world data at higher Q², allow a systematic determination of the 1/Q² corrections, and provide the first constraints on 1/Q⁴ corrections. The results suggest that higher-twist effects in the neutron are surprisingly small, and that quark-hadron duality may be approximately valid, even down to Q² ∼ 0.5 GeV²

[en] We present measurements of the recoil proton polarization for the d(polarized y, polarized p)n reaction at thetac.m. = 90 degrees 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(y,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

[en] The recoil proton polarization was measured in the d(epol,e' ppol)n reaction in Hall A of the Thomas Jefferson National Accelerator Facility (JLab). The electron kinematics were centered on the quasielastic peak (x_Bj ∼ 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, p_m, was centered at zero while for Q²=1.00 (GeV/c)² two values of p_m were chosen: 0 and 174 MeV/c. At low p_m, the Q² dependence of the longitudinal polarization, P_z', is not well described by a state-of-the-art calculation. Further, at higher p_m, a 3.5 sigma discrepancy was observed in the transverse polarization, P_x'. Understanding the origin of these discrepancies is important in order to confidently extract the neutron electric form factor from the analogous d(epol,e' npol)p experiment

[en] The generalized forward spin polarizabilities γ₀ and (delta)_LT of the neutron have been extracted for the first time in a Q² range from 0.1 to 0.9 GeV². Since γ₀ is sensitive to nucleon resonances and (delta)_LT is insensitive to the Δ 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 (delta)_LT show significant disagreement with Chiral Perturbation Theory calculations, while the data for γ₀ at low Q² are in good agreement with a next-to-lead order Relativistic Baryon Chiral Perturbation theory calculation. The data show good agreement with the phenomenological MAID model

[en] We extract the Bjorken integral Γ₁^p-n in the range 0.17 < Q² < 1.10 GeV² from inclusive scattering of polarized electrons by polarized protons, deuterons and ³He, for the region in which the integral is dominated by nucleon resonances. These data bridge the domains of the hadronic and partonic descriptions of the nucleon. In combination with earlier measurements at higher Q², we extract the non-singlet twist-4 matrix element f₂