Crossing versus noncrossing quark-line diagrams in p-barp→two mesons

Diagrams for p-barp→two mesons (a) without and (b) with quark lines crossing each other are compared. Theoretical arguments favor noncrossing diagrams (type a). Data on p-barp→two pseudoscalars mesons agree (disagree) with dominance of diagrams of the type a (type b). The predictions of the two models for p-barp→ωω differ strongly