Shadowing in the Deuteron and the New $F_2^n/F_2^p$ Measurements

The quantity $2F_2^d(x,Q^2)/F_2^p(x,Q^2)-1$ is calculated in the region of low $x$ and low- and moderate $Q^2$ relevant for recent NMC and E665 measurements as well as for the expected final results of the precise NMC analysis of their low $x$ data. The calculations include nuclear shadowing effects and a suitable extrapolation of the structure functions of free nucleons to the low $Q^2$ region. The theoretical results are in a good agreement with the NMC data. The shadowing correction to the experimental estimate of the Gottfried sum is quantified.