Absorption Model andU(6, 6)for the Reactionspp¯→YY¯

The $U\left(6.\mathrm{} 6\right)$ symmetry is used to write down peripheral amplitudes for the processes $p\overline{p}\to (K, K^{*})Y\overline{Y}$. The requirements of unitarity are approximately enforced on the amplitudes so derived by the inclusion of absorptive corrections. Assuming a value of $\frac{G_{\pi N{N}^2}}{4\pi }$ and adopting a prescription for dealing with the mass splitting in $U(6, 6)$, we find satisfactory agreement for the angular distributions in all cases and obtain satisfactory absolute values for $\Lambda \overline{\Lambda }$ and ${\Sigma }^{+}{\overline{\Sigma }}^{-}$, but not $\Lambda {\overline{\Sigma }}^0$. The energy variation of the cross section is satisfactorily reproduced for $\Lambda \overline{\Lambda }$ and ${\Sigma }^{+}{\overline{\Sigma }}^{-}$ in the intermediate momentum range from 3.0 to 5.7 GeV/c; but not for $\Lambda {\overline{\Sigma }}^0$.