Deuteron photodisintegration and quark models

We have examined the behavior of the forward-to-backward ratio R of the cross section for the ${}_{}{}^2{}_{}{}^{}\mathrm{H}$(γ,p)n reaction. The data show a weak dependence of R on the photon energy and group around a value of 1.5 which agrees with the prediction of a simple quark model. An energy dependence of R is predicted in the quark-gluon string model and is shown to be connected to the ratio of d/u quark distributions in the proton.