QUASI-ELASTIC DELTA-EXCITATION IN THE CHARGE RESPONSE OF THE NUCLEUS

We have studied the general relation between nuclear and free-nucleon longitudinal and transverse responses and shown that nuclear Fermi motion implies admixtures from transverse nucleon currents in the longitudinal (or Coulomb) nuclear response and vice versa. We give the general expression for the relation between the nucleon and nuclear responses in the Fermi-gas model including the case of isobar excitation. In the particular case of the DELTA-resonance we have shown that at large transferred momenta (i.e. great-than-or-equal-to 1 GeV/ c) an important tail is produced beyond the nucleon quasi-elastic peak which has nothing to do with Coulomb strength.