The Q^2-dependence of the Generalised Gerasimov-Drell-Hearn Integral for the Proton

Abstract

The dependence on Q^2 (the negative square of the 4-momentum of the exchanged virtual photon) of the generalised Gerasimov-Drell-Hearn integral for the proton has been measured in the range 1.2 GeV^2 < Q^2 < 12 GeV^2 by scattering longitudinally polarised positrons on a longitudinally polarised hydrogen gas target. The contributions of the nucleon-resonance and deep-inelastic regions to this integral have been evaluated separately. The latter has been found to dominate for Q^2 > 3 GeV^2, while both contributions are important at low Q^2. The total integral shows no significant deviation from a 1/Q^2 behaviour in the measured Q^2 range, and thus no sign of large effects due to either nucleon-resonance excitations or non-leading twist.

9 pages, 3 figures, 1 table

References in corpus (1)

• Generalized Drell-Hearn-Gerasimov Sum Rule at Order {\cal O}(p^4) in Chiral Perturbation Theory

Cited by in corpus (10)

• Study of the Decay phi --> pi0 pi0 gamma with the KLOE Detector
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• The GDH Sum Rule and Related Integrals
• Measurement of the Proton Spin Structure Function $g_1(x,Q^2)$ for $Q^2$ from 0.15 to 1.6 GeV${}^2$ with CLAS
• Evidence for Quark-Hadron Duality in the Proton Spin Asymmetry $A_1$
• QCD radiative and power corrections and Generalized GDH sum rules
• Bjorken sum rule at low Q^2
• Accessing the Longitudinally Polarized Photon Content of the Proton
• Measurement of the nucleon spin structure functions for 0.01<$Q^2$<1 GeV${}^2$ using CLAS