RESULTS AND INTERPRETATIONS OF THE SPIN STRUCTURE EXPERIMENTS AT SLAC

Technical Report · Wed May 21 00:00:00 EDT 2003

DOI:https://doi.org/10.2172/813139· OSTI ID:813139

Kolomensky, Yury G ^[1]

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1. SLAC

In the recent experiments E154 and E155 at SLAC the spin-dependent structure functions g{sub 1}{sup n}, g{sub 1}{sup p}, and g{sub 1}{sup d} of the neutron, proton, and deuteron were measured by scattering longitudinally polarized 48:3 GeV electrons off longitudinally polarized targets. We report on the measurement of g{sub 1}{sup n} by E154, and on the preliminary results on g{sub 1}{sup 0} from E155. The SLAC results provide the most precise determination to date of the polarized structure functions. We observe relatively large values of g{sub 1}{sup n} at low x that call into question the reliability of data extrapolation to x -> 0. Such divergent behavior disagrees with predictions of the conventional Regge theory, but is qualitatively explained by perturbative QCD. We perform a Next-to-Leading Order perturbative QCD analysis of the world data on the nucleon spin-dependent structure functions. Using the parameterizations of the helicity-dependent parton distributions obtained in the analysis, we evolve the data to Q{sup 2} = 5 GeV{sup 2}, determine the first moments of the polarized structure functions of the proton and neutron, and find agreement with the Bjorken sum rule.

• Research Organization: Stanford Linear Accelerator Center, Menlo Park, CA (US)
• Sponsoring Organization: USDOE Office of Science (US)
• DOE Contract Number: AC03-76SF00515
• OSTI ID: 813139
• Report Number(s): SLAC-PUB-9860
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
DEUTERONS
ELECTRONS
EXTRAPOLATION
NUCLEONS
PARTONS
POLARIZED TARGETS
PROTONS
QUANTUM CHROMODYNAMICS
RELIABILITY
SCATTERING
SPIN
STANFORD LINEAR ACCELERATOR CENTER
STRUCTURE FUNCTIONS
SUM RULES