Radiative Four--Meson Amplitudes in Chiral Perturbation Theory

Abstract

We present a general discussion of radiative four--meson processes to $O(p^4)$ in chiral perturbation theory. We propose a definition of ``generalized bremsstrahlung'' that takes full advantage of experimental information on the corresponding non--radiative process. We also derive general formulae for one--loop amplitudes which can be applied, for instance, to $\eta \text{ra}3\pi \gamma$, $\pi \pi \text{ra}\pi \pi \gamma$ and $K\text{ra}3\pi \gamma$.

Comments: 8 pages, LaTex file, 1 figure. Full postscript version at this URL http://hpteor.lnf.infn.it/dafnepapers.html