Present status of (ee'p) experiments

Abstract

The new measurements of the quasi free process (ee'p) on ¹²C and ¹⁶O, combined with the recent development of theoretical formalism have demonstrated that the reaction mechanism and the off shell effects are now well understood for outer shells (in the precision of about 10 %) where the single hole state seems to be a reasonable assumption. It appears that the corresponding absolute spectroscopic strength is definitively smaller than 1. A reliable calculation of these quantities will be precious for the interpretation of these quasi free experiments ; some estimations¹³). of the target ground state correlations show that the 1p_1/2 is a little less occupied than the 1p_3/2 in ¹⁶O but the occupation numbers are both around 0.9. Concerning the inner shells, data are now available on a very large range, and ¹⁶O is one of the best candidate to test the correction of rescattering process and the calculations with correlations.

The understanding of the inner shells is very important because we have noticed that the theoretical spectral function of the s-state is very dependent of the bound state model in opposition with the corresponding p-state spectral function (as shown in table 1) where the variation reaches only 20 % at 280 MeV/c.