Neutronproton structure function ratio at large x

We re-examine the large-x neutron/proton structure function ratio extracted from the latest deuteron data, taking into account the most recent developments in the treatment of Fermi motion, binding and nucleon off-shell effects in the deuteron. Our findings suggest that as x → 1 the ratio of the neutron to proton structure functions (F2nF2p) is consistent with the perturbative QCD expectation of 37, but which is larger than the value of 14 obtained in earlier analyses.