Contribution of high energy configurations to longitudinal and transverse form factors in p- and sd-shell nuclei

Abstract

Longitudinal and transverse electron scattering form factors for some selected positive and negative parity states of stable odd-A nuclei ($^{7}$Li, $^{13}$C and $^{17}$O) in the p- and sd-shells are investigated by considering the higher energy configurations outside the p- and sd-shells. The higher energy configurations, referred to as core polarization effects, are considered by means of a microscopic theory that includes excitations from the core 1$s$-1p, 2$s$-1$d$ orbits to the higher allowed orbits with 4$\hbar \omega$ excitations. The calculations are performed in the p- and sd-shell model spaces by employing Cohen-Kurath, Reehal and Wildenthal interactions respectively, while the core polarization effects are calculated with the modified surface delta interaction as residual interaction. The predicted form factors are compared with the available experimental data and it is shown that the inclusion of the higher excited configurations is very essential in the calculations of the form factors and the reduced transition probabilities to obtain reasonable description of the data with no adjustable parameters.