Electronuclear sum rules. Improved realization and statement. Experiment and theory for4He
The experimental (e, e′) data in the region of highω, necessary for a reliable check of sum rules, are either unavailable or dominated by pion degrees of freedom. To calculate the corresponding sums over (e, e′) spectra, a reliable extrapolation of spectra to this region is proposed. It is based on a quasi-y-scaling type behavior of the spectra. It is shown that the sum rule version corresponding to the summation of the spectra at constantE0 andθ, being simplest from the experimental viewpoint, can be made accurate enough if an experimental spectrum is used to estimate the parameters involved in it. It is found that for4He nucleus, one of the existing groups of the experimental spectra is in a good agreement with the model-independent sum rule which corresponds to the single-particle approximation for the interaction of a nucleus with an electromagnetic field, while the second group of spectra leads to a considerable deviation from the sum rule.