The reactionγγ→ππat low energy

Abstract

The results of a previous calculation by two of the present authors are presented in a form more suitable for comparison with recent experiments on γγ→${\pi }^{+}$ ${\pi }^{\mathrm{-}}$ and γγ→${\pi }^0$ ${\pi }^0$. The relation of the process $K_S$→γγ to these calculations is recalled briefly.