New evaluation of the Baldin sum rule

Abstract

The Baldin sum rule for the nucleon has been recalculated at the light of the most recent photoabsorption cross section measurements. The proton value $(\alpha +\beta {)}_p=13.69\mathrm{}\pm 0.14$ is smaller but consistent with the one usually quoted in literature. However, the value for the neutron $(\alpha +\beta {)}_n=14.40\mathrm{}\pm 0.66$ turns out to be three standard deviations away from the previously calculated one.