Semi-inclusive deep inelastic electron scattering off the deuteron and the neutron to proton structure function ratio

The production of slow nucleons in semi-inclusive deep inelastic electron scattering off the deuteron is investigated in the region x ≳ 0.3. It is shown that within the spectator mechanism the semi-inclusive cross section exhibits a scaling property even at moderate values of Q2 (∼ few (GeV/c)2) accessible at present facilities, like CEBAF. Such a scaling property can be used as a model-independent test of the dominance of the spectator mechanism itself and provides an interesting tool to investigate the neutron structure function. The possibility of extracting model-independent information on the neutron to proton structure function ratio from semi-inclusive experiments is illustrated. The application of the spectator scaling to semi-inclusive processes off complex nuclei is outlined.