Compton scattering from nuclei and photo-absorption sum rules

摘要

We revisit the photo-absorption sum rule for real Compton scattering from the proton and from nuclear targets.nIn analogy with the Thomas-Reiche-Kuhn sum rule appropriate at low energies, we propose a new “constituentnquark model” sum rule that relates the integrated strength of hadronic resonances to the scattering amplitude onnconstituent quarks. We study the constituent quark model sum rule for several nuclear targets. In addition, wenextract the α = 0 pole contribution for both proton and nuclei. Using the modern high-energy proton data, wenfind that the α = 0 pole contribution differs significantly from the Thomson term, in contrast with the originalnfindings by Damashek and Gilman.