Neutron elastic form factors: Significant progress has been
made in determining the electric and magnetic form factors of the neutron,
quantities relevant both for testing quark models and for accurate
interpretation of many other experiments. Experiments have measured
utilizing polarized electron beams, polarized He targets and
recoil neutron polarimetry. Cross section and spin asymmetry experiments
have produced new, high quality data on .
Nucleon resonances: Polarization experiments have observed a
non-zero E2 component in the transition at
, which is a necessary consequence of the quark-quark hyperfine
interaction. Many theoretical efforts are underway to interpret these and
future experiments in terms of and deformation.
Nucleon polarizabilities: Precise measurements of the electric
and magnetic polarizabilities of the proton provide fundamental new
information on nucleon structure that represents a stringent test of chiral
perturbation theory.
Spin structure functions: The first measurements of the spin
structure function of the neutron were performed, and new proton spin
structure function measurements confirm that the Ellis-Jaffe sum rule is
indeed violated. Analysis of these and related data indicate that the
fraction of the nucleon's spin carried by the quarks is approximately
and that the strange sea has a polarization of approximately .
Tests of the Bjorken sum rule: The Bjorken sum rule, a
rigorous consequence of QCD, was tested for the first time; the sum rule
appears to be valid at the level.
Threshold photo- and electro-production: New
measurements of the -wave photoproduction amplitude and the
amplitude coupled with calculations of higher order terms in chiral
perturbation theory have produced new understanding of the dynamics of
these fundamental processes and the relation to low energy theorems.
Gottfried sum rule: A recent precision measurement of the ratio
of proton to deuteron structure functions indicates a large asymmetry
between the up and down sea quark distributions.
