Valence quark ratio in the proton

Abstract

Beginning with precise data on the ratio of structure functions in deep inelastic scattering (DIS) from ${}^3$He and ${}^3$H, collected on the domain $0.19\le x_B\le 0.83$, where $x_B$ is the Bjorken scaling variable, we employ a robust method for extrapolating such data to arrive at a model-independent result for the $x_B=1$ value of the ratio of neutron and proton structure functions. Combining this with information obtained in analyses of DIS from nuclei, corrected for target-structure dependence, we arrive at a prediction for the proton's valence-quark ratio: ${d_v/u_v|}_{x_B\to 1}=0.230(57)$. Requiring consistency with this result presents a challenge to many descriptions of proton structure.

Comments: 6 pages, 3 figures