Singlet cross section and the tensor interaction in $\overline{\mathrm{p}} \mathrm{p} \rightarrow \bar{\Lambda} \Lambda$

In this short paper, we demonstrate using irreducible tensorial techniques and in a model-independent way, why tensor interactions and also orbital-angular momentum-changing vector interactions are absent in the singlet unpolarized differential cross section for the reaction $\overline{\mathrm{p}} \mathrm{p} \rightarrow \bar{\Lambda} \Lambda$.