The rare decay $\eta \to \pi \pi \gamma \gamma$ in chiral perturbation theory

Abstract

We investigate the rare radiative eta decay modes $\eta \to {\pi }^{+}{\pi }^{-}\gamma \gamma$ and $\eta \to {\pi }^0{\pi }^0\gamma \gamma$ within the framework of chiral perturbation theory at $O(p^4)$. We present photon spectra and partial decay rates for both processes as well as a Dalitz contour plot for the charged decay.

Comments: 26 pages, RevTex, 10 figures, to appear in Phys. Rev. D