Q²-dependence of the Gerasimov-Drell-Hearn sum rule
Date
1998
Authors
Ma, W.
Lu, D.
Thomas, A.
Li, Z.
Editors
Advisors
Journal Title
Journal ISSN
Volume Title
Type:
Journal article
Citation
Nuclear Physics A, 1998; 635(4):497-508
Statement of Responsibility
W.X. Ma, D.H. Lu, A.W. Thomas, Z.P. Li
Conference Name
Abstract
We test the Gerasimov-Drell-Hearn (GDH) sum rule numerically by calculating the total photon absorption cross sections σ<inf>1/2</inf> and σ<inf>3/2</inf> on the nucleon via photon excitation of baryon resonances in the constituent quark model. A total of seventeen, low-lying, non-strange baryon resonances are included in this calculation. The transverse and longitudinal interference cross section, σ<sup>TL</sup><inf>1/2</inf>, is found to play an important role in the study of the Q<sup>2</sup> variation of the sum rule. The results show that the GDH sum rule is saturated by these resonances at a confidence level of 94%. In particular, the P<inf>33</inf>(1232) dominates at small Q<sup>2</sup>. The GDH integral has a strong Q<sup>2</sup>-dependence below Q<sup>2</sup> = 1.0 GeV<sup>2</sup> and changes its sign around Q<sup>2</sup> = 0.3 GeV<sup>2</sup>. It becomes weakly Q<sup>2</sup>-dependent for Q<sup>2</sup> > 1.0 GeV<sup>2</sup> because of the quick decline of the resonance contributions. © 1998 Published by Elsevier Science B.V.