The Q2-dependence of the generalised Gerasimov–Drell–Hearn integral for the proton HERMES Collaboration
نویسندگان
چکیده
The dependence on Q2 (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 GeV2 < Q2 < 12 GeV2 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 Q2 > 3 GeV2, while both contributions are important at low Q2. The total integral shows no significant deviation from a 1/Q2 behaviour in the measured Q2 range, and thus no sign of large effects due to either nucleon-resonance excitations or nonleading twist. 2000 Elsevier Science B.V. All rights reserved. * Corresponding author. E-mail address: [email protected] (M.G. Vincter). A. Airapetian / Physics Letters B 494 (2000) 1–8 3 PACS: 13.60.Hb; 13.88.+e; 25.20.Dc; 25.30.Fj
منابع مشابه
03 7 v 1 1 8 A ug 2 00 0 The Q 2 - dependence of the Generalised Gerasimov - Drell - Hearn Integral for the Proton
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