The Q2-dependence of the generalised Gerasimov–Drell–Hearn integral for the proton

A. Airapetian, N. Akopov, I. Akushevich, M. Amarian, J. Arrington, E.C. Aschenauer, H. Avakian, R. Avakian, A. Avetissian, E. Avetissian, P. Bailey, B. Bains (+177 others)
2000 Physics Letters B  
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
more » ... 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.
doi:10.1016/s0370-2693(00)01111-4 fatcat:je4ss7aedzgq7hrlczyhqstzka