A study of the internal spin structure of the proton through inclusive and semi-inclusive polarized deep-inelastic muon-proton scattering

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1988

OSTI ID:5834687

Papavassiliou, V

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 g{sub 1} 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.

• Research Organization: Yale Univ., New Haven, CT (USA)
• OSTI ID: 5834687
• Country of Publication: United States
• Language: English

Related Subjects

645103* -- High Energy Physics-- Particle Interactions & Properties-Experimental-- Strong Interactions & Baryon & Meson Properties
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ANGULAR MOMENTUM
ASYMMETRY
BARYONS
BEAMS
DATA
ELEMENTARY PARTICLES
EQUATIONS
EXPERIMENTAL DATA
FERMIONS
FUNCTIONS
HADRONS
HELICITY
INCLUSIVE INTERACTIONS
INFORMATION
INTERACTIONS
LEPTON BEAMS
LEPTON-BARYON INTERACTIONS
LEPTON-HADRON INTERACTIONS
LEPTON-NUCLEON INTERACTIONS
MUON BEAMS
MUON-NUCLEON INTERACTIONS
MUON-PROTON INTERACTIONS
NEUTRONS
NUCLEONS
NUMERICAL DATA
PARTICLE BEAMS
PARTICLE INTERACTIONS
PARTICLE PROPERTIES
PARTICLE STRUCTURE
POSTULATED PARTICLES
PROTONS
QUARKS
SEMI-INCLUSIVE INTERACTIONS
SPIN
STRUCTURE FUNCTIONS
SUM RULES