Experimental Studies of the Gerasimov-Drell-Hearn Sum Rules
The Gerasimov-Drell-Hearn sum rule, which was originally derived at Q 2 = 0, has been extended recently to finite Q 2. The measurement of its Q 2 behavior provides a powerful way to investigate the transition between the partonic and hadronic description of QCD. I recall first the theoretical grounds of GDH. Then new experimental results on both the original and extended sum rules are discussed. Here, I focus on the results obtained in Hall A at Jefferson Lab. I will conclude by presenting the experimental perspectives, both at low Q 2 and at large photon energies.
KeywordsDeep Inelastic Scattering Chiral Perturbation Theory High Resolution Spectrometer Hadronic Degree Pion Photo
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