[en] The internal spin structure of the proton was studied in a deep-inelastic scattering experiment a CERN, the European Laboratory for Nuclear Research, by the European Muon Collaboration, using a longitudinally polarized muon beam and a longitudinally polarized target at irradiated ammonia. The spin asymmetry was studied as a function of the Bjorken scaling variable x and the results were in agreement over the region of overlap with previous experiments that used lower-energy polarized electron beams. The higher energies of the experiment allowed to study with precision the previously unexplored region of x below 0.1 and to compute the integral of the spin-dependent structure function g₁ of the proton. This integral was found to be in disagreement with the Ellis-Jaffe sum rule which could imply either a breakdown of the SU(3) symmetry in the decays of the members of the baryon octet or a significant polarization of the strange-quark sea of the proton opposite to the proton spin. In either case and assuming the validity of the Bjorken sum rule that relates the integrals of the spin-dependent structure functions of the proton and the neutron, the total helicity of all the quarks is found to account for only a small fraction of the proton helicity. In addition, spin asymmetries in the semi-inclusive reactions where a hadron of definite sign is observed in the final state were studied. The results are consistent with the down quarks being polarized opposite to the proton spin, as expected by symmetry arguments. Implication of the results on different areas in particle physics are presented. Some future prospects for spin physics are discussed and predictions are given for deep-inelastic-scattering experiments on polarized deuterium targets and the spin structure of the neutron

[en] Preliminary results are presented on the measurement of the cross-section ratio σ_n/σ_p inelastic μN scattering obtained by the E-665 experiment using the Fermilab 490 GeV/c muon beam and liquid H₂ and D₂ targets. The results extend the previously measured x range by two orders of magnitude, down to 2 x 10^-5, at Q² > 10^-2 GeV²/C². The ratio is consistent with 1 throughout the new range

[en] The working group discussed several topics related to charm production that can provide important input for our understanding of QCD. It was recognized that studies of both open and hidden charm in a high-statistics experiment will be essential in order to understand the production mechanisms. Nuclear effects were also discussed and a connection was made to similar effects observed in other reactions

[en] We propose to measure, for the first time, the spin-dependent structure functions g₁ of the neutron and its integral over x. In addition, we propose to repeat the EMC measurement of the structure function g₁ of the proton and its integral with higher statistical accuracy and better control over the systematic errors. The two measurements will allow a test of the validity of the Bjorken sum rule with a statistical and systematic uncertainty of about 10% each

[en] The NA2' experiment at CERN has measured the spin asymmetry in deep-inelastic polarized muon-proton scattering and extracted the spin-dependent structure function g₁ of the proton. The integral of g₁ over x was found to be 0.114 +- 0.012 +- 0.026, in disagreement with the Ellis-Jaffe sum rule. An implication is that the quarks account for only a small fraction of the proton spin

[en] In this paper the status of the authors' current knowledge of the spin structure of the nucleon, obtained in deep-inelastic lepton-nucleon scattering, is summarized, with emphasis on new information that became available recently from EMC. The implications of these results for the commonly accepted picture of the nucleon are discussed. Finally, plans for new experiments that could be performed in the near future are presented

[en] The G⁰ experiment at Jefferson Lab uses elastic, parity-violating electron-proton scattering to study the strange-quark contribution to the proton form factors. A dedicated, special-purpose spectrometer was built for this project. We present results from the recently completed forward-scattering-angle run and compare them with previous experiments. Results from a combined analysis of all available data are also shown and the current status of the experiment and future plans are discussed

[en] A recent EMC experiment has found that the integral of the spin-dependent structure function g₁ of the proton violates the Ellis-Jaffe sum rule. It is shown here that this result can be strengthened when combined with older data from SLAC. (orig.)

[en] The strangeness content of the nucleon and the contribution of strange quarks to various nucleon quantum numbers, besides being of fundamental interest, also affects calculations of cross sections of processes that are important in searches for new physics. Here we focus on direct searches for cold dark matter, in the scenario in which the lightest supersymmetric neutral particle dominates the CDM density in the universe and point out that interpretation of searches, as well as the choice of optimal materials for future experiments, are hobbled by uncertainties in the contribution of strange quarks to the nucleon spin. We show how a future low-energy neutrino experiment using a liquid-Ar TPC can make important contributions in determining this quantity with much better precision and reduced theoretical uncertainties.

[en] Many of the high energy physics questions addressed by the Fermilab Fixed Target Experiments are also of interest to the members of the nuclear community. Some recent highlights of the program, including studies of A-dependence of cross sections, evidence for parton rescattering in nuclear media, studies of heavy quark production, evidence for color transparency, and insights into QCD from meson systems, are discussed