Q2-Dependence of the Gerasimov-Drell-Hearn Sum Rule
- Received Date: 1998-07-16
- Accepted Date: 1900-01-01
- Available Online: 1999-09-05
Abstract: We test the Gerasimov-Drell-Hearn (GDH) sum rule numerically by calculating the total photon absorption cross sections σ1/2 and σ3/2 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 mis calculation.The transverse and longitudinal interference cross section, σ, is found to play an important role in the study of the Q2 variation of the sum rule. The results show that the GDH sum rule is saturated by these resonances at a confidence level of 94%. Inparticular , the P33,(1232) excitation largely saturates the stun rule at Q2=0, and dominates at small Q2. The GDH integers has a strong Q2-dependence below Q2=1.0GeV2 and changes its sign around Q2=0.3GeV2. It becomes weakly Q2-dependence for Q2>1.0GeV2 because of the qinck decline of resonance contributions.