Nucleon distribution amplitude and diquark clustering

We explore the possibility of diquark clustering as a source of the asymmetry in the quark distribution amplitudes found by the QCD sum-rule technique. We consider a simple light-cone wave-function model for the nucleon and find that a two-quark correlation in the spin-zero state provides a significantly better account of the Chernyak-Zhitnitsky asymmetry than does a previous symmetric quark model with uncorrelated quarks.