Electric dipole photoabsorption and the quark structure of nucleons

Sum rules for electric dipole photoabsorption in the constitutent-quark model are considered. The experimental data on electric dipole photoabsorption on the proton at photon energies up to 1.2 GeV are well described in the quark model by the sum rules for the zeroth and first negative moments. The first sum rule predicts equality of the contributions to the integrals for photoabsorption on the proton and on the neutron, and this makes it important to obtain high-quality data on photoabsorption on the neutron. An important role in the description is played by inclusion of an admixture of the multiplet [70, 0+] in the nucleon, which is also necessary from the point of view of the mass formulas for the baryons