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 constantE ₀ 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.