Parameterization of [sigma(1/2) - sigma(3/2)] for Q**2 >= 0 and nonresonance contribution to the GDH sum rule
Feb, 1999Citations per year
Abstract:
A description of the virtual photon absorption cross section difference \sigma_{1/2}-\sigma_{3/2} for the proton and the neutron is obtained with a parameterisation based on a Regge type approach. The parameterisation is obtained from global fits to the cross section data derived from the spin asymmetries measured in DIS of longitudinally polarised leptons from polarised ^1H, ^3He and ^2H targets in the range 0.3 GeV^2 < Q^2 < 70 GeV^2 and 4 GeV^2 < W^2 < 300 GeV^2. The fits give a reliable description of the data and provide predictions for the photo-production through a smooth Q^2-transition. The contribution above the resonance region to the Gerasimov-Drell-Hearn sum rule for real and virtual photons has been evaluated. For the real photons this contribution accounts for a large fraction of the discrepancy between the sum rule expectations and the single pion photo-production analysis estimatesNote:
- Latex 12 pages, 4 figures. To be published in Phys. Lett. B
- 13.60.Hb
- 13.88.+e
- 25.20.Dc
- 25.30.Fj
- Deep inelastic scattering
- Sum rules
- Asymmetries
- Photo-absorption
- lepton p: deep inelastic scattering
- lepton n: deep inelastic scattering
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