Kaon Decay into Three Photons Revisited

Abstract

We evaluate the rare radiative kaon decays K_{L,S} -> 3 gamma. Applying the requirements of gauge invariance and Bose symmetry, we derive a general form of the decay amplitude, including both parity-conserving and parity-violating contributions. We employ a chiral-Lagrangian approach combined with dimensional analysis arguments to estimate the branching ratios of these decays in the standard model, obtaining values as large as B(K_L -> 3 gamma) ~ 1 x 10^{-14} and B(K_S -> 3 gamma) ~ 2 x 10^{-17}, which exceed those found previously by a few orders of magnitude. Measurements on the branching ratios which are significantly larger than these numbers would likely hint at the presence of new physics beyond the standard model.

10 pages, no figures