Valence Quark Ratio in the Proton

Abstract

Beginning with precise data on the ratio of structure functions in deep inelastic scattering (DIS) from 3He and 3H, collected on the domain 0.19 ≤ x B ≤ 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 valence-quark ratio: dν /uνq | x B → 1 = 0.230 (57). Requiring consistency with this result presents a challenge to many descriptions of proton structure.