$\gamma \gamma \to \pi \pi \pi$ to One Loop in Chiral Perturbation Theory

Abstract

The $\gamma \gamma \to {\pi }^0{\pi }^0{\pi }^0$ and $\gamma \gamma \to {\pi }^{+}{\pi }^{-}{\pi }^0$ amplitudes are discussed in the general context of Chiral Perturbation Theory (ChPT) to $O(p^6)$. Chiral loops are found to play a major role. This makes these processes a good test of ChPT, mainly in its anomalous sector. We correct earlier numerical results at tree level and determine the one-loop results as well.

Comments: 12 pages, 2 postscript figures, uses epsfig.sty. The cross-section for the neutral channel has been corrected but the main conclusions have not changed