1 research outputs found
--Dependence of the Gerasimov-Drell-Hearn Sum Rule
We test the Gerasimov-Drell-Hearn (GDH) sum rule numerically by calculating
the total photon absorption cross sections and 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, , is found to play an important role in the
study of the 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 excitation largely saturates the sum rule at
, and dominates at small . The GDH integral has a strong
-dependence below and changes its sign around . It becomes weakly -dependent for because of
the quick decline of the resonance contributions. We point out that the
variation of the GDH sum rule is very important for understanding the nucleon
spin structure in the non-perturbative QCD region.Comment: revtex, 17 pages, 3 ps figs include