2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/82733The splitting between the charge-longitudinal and spin-transverse responses is explained in a model whose inputs are the effective interactions in the particle-hole channels in the first order boson loop expansion. The interplay between $ω$-meson exchange and box diagrams mainly governs the longitudinal response, while in the transverse one the direct $Δ$ excitations almost cancel the one-loop correction and the response is ruled by the $ρ$-meson rescattering.LaTex file with 25 .ps figures, to appear on Proc. of XIII ISHEPP seminars - Dubna 1996Nuclear Theorytext